99 Brain Games Guaranteed to Boost Your Brain Power
Every month, Reader's Digest publishes a few brain games in the magazine to help you become a genius. See how many you can solve.
Your brain isn’t a muscle—in fact, it’s mostly fat!—but the right kind of mental exercise can help keep it in shape. These puzzles are designed to give your problem-solving, reasoning, and concentration skills a workout. And they come in varying degrees of difficulty, so pace yourself! Also, try to solve these logic puzzles that will keep you guessing.
The good life
Each of five neighborhood dogs is enjoying one of the following activities. Based on the clues, can you figure out what each pooch is doing?
- Getting ears scratched
- Playing catch
- Taking a nap
- Burying a chew toy
- Going for a walk
- Pepper is either playing catch or burying a chew toy.
- Neither Ginger nor Saber nor Bear is on a walk.
- One of the dogs named after a spice is getting her ears scratched (and loving it).
- A dog who is not named for a spice is playing catch.
- Bear is getting some exercise.
Try out some of the most challenging jigsaw puzzles you can buy.
Saber is taking a nap, Ginger is getting her ears scratched, Nutmeg is going for a walk, Pepper is burying a chew toy, and Bear is playing catch.
The names of six different colors are hidden between consecutive words in the silly story below. Can you find them all? Example: Much art reuses themes and motifs from previous eras. (chartreuse)
Sure, it’s fancy and all, but my brother’s car lets out a strange noise when you start it. I find I go too hard on him sometimes, but he did waste a lot of money customizing the exterior, only to leave the generic rims on it and forgo all routine maintenance. Hitting the road? Here are some of the best road trip games to play.
Cyan (fancy and), scarlet (brother’s car lets), indigo (find I go), teal (waste a lot), crimson (generic rims on), tan (it and). See if you can find the turtle hidden in this picture.
Each letter (A–G) has one of the seven values listed above. No two letters have the same value. Match each letter to a number to make the equations work. These are the best-reviewed board games to play during quarantine.
A = 2, B = 5, C = 7, D = 4, E = 6, F = 8, G = 11. If you want to try something a little easier, check out these riddles for kids.
These four cogs are going to help you crack a safe. Naturally, when you turn one cog, the other three move as well. Imagine you turn all four the number of notches specified in the center of each cog in the direction indicated. The teeth that are then positioned next to the circles reveal a four-digit safe combination. What is it? Read up on these fascinating facts about your favorite games.
8, 2, 8, 1. Try these easy riddles (with answers) that anyone can solve.
Expand and conquer
Each of these sequences follows the same rule, and each one continues until it resolves to a number under ten, at which point it naturally comes to a stop. How should the sequence starting with 87 continue? For more of a challenge, check out the hardest puzzles you can get on Amazon.
Sort it out
The eight tiles above have been sorted into two groups according to a rule. Part of this rule is that in Group A, the three dots on each tile are arranged clockwise starting with the dot on top, and in Group B, they’re arranged counterclockwise.
Group B. The dots on each tile are in alphabetical order by color (Blue, Green, Orange, Purple, Red, Yellow), with Group A going clockwise from the top dot and Group B counterclockwise.
Here’s the deal
Four playing cards, one of each suit, lie in a row on a table. They are a three, a four, a five, and a six. Using these clues, can you determine the cards’ suits and their order?
- The cards on either side of the four are black.
- The club is to the right of the three but not next to it.
- The spade is to the left of the heart.
- The middle two cards add up to an even number. Neither of them is a club.
Left to right: Three of diamonds, six of spades, four of hearts, five of clubs.
The fashionable snowman
Noel is about to put the finishing touches on the snowman he built. He has already placed the buttons and sticks (as shown), but he has a few other decorations as well. They are:
- A top hat
- A festive scarf
- A carrot, for the nose
- A pipe
- A vest
Noel might use all of these items, though he will certainly use no fewer than three. How many different combinations are possible?
Fill in the blanks
How many common English words can you make by adding a letter to each of the blanks below? We found seven. Proper nouns don’t count.
Daily, dairy, daisy, deify, deity, doily, drily.
Rephrase each item below as a pair of rhyming words. Hint: Each item’s number is also the number of syllables in each word in the answer.
- A comfortably tight embrace
- A safari animal born in September or October
- A softcover book for a flannel-wearing woodworker
- A well-read office assistant
- A formal statement given by a witness at an official gathering
1. Snug hug
2. Libra zebra
3. Lumberjack paperback
4. Literary secretary
5. Ceremonial testimonial
We leave you hanging
Each of these paintings must be hung on the wall on one of the hooks shown. Naturally, the hook goes in the middle of the top edge of the painting so it hangs straight. Paintings can touch but cannot overlap. How can you hang all five without moving any hooks?
Ruby and Lewis are expecting … triplets! They already know what they will name their children, but they aren’t sharing the names until the babies are born. For now, all they’ll say is this:
- All three babies are boys.
- Their names are six letters long and anagrams of one another.
- Their names include both their parents’ initials but none of the other letters in their parents’ first names.
What will Ruby and Lewis name their triplets?
Daniel, Emily, Marciano, and Christina are all wearing solid-colored shirts. The colors of their four shirts are red, yellow, green, and blue. Only the person wearing blue tells the truth, while the other three lie. They make the following statements:
Daniel: “Marciano is wearing red.”
Emily: “Daniel is not wearing yellow.”
Marciano: “Emily is wearing blue.”
Christina: “I’m going to wear blue tomorrow.”
Can you determine each person’s shirt color, and whether we can expect to see Christina in blue tomorrow?
Daniel is wearing yellow, Emily is in red, Marciano is in green, and Christina is in blue. Christina will wear a blue shirt again tomorrow.
Odd die out
Here’s a flat template that can be folded into a cube. Which of the views below does not represent the resulting cube?
C. These brainteasers for kids will help to beat boredom.
In a state
All the letters in Ohio appear—albeit in a different order—in both North Carolina and South Carolina (but not in Washington, which has only one o). Can you figure out the state whose letters appear in a total of three state names?
This, not that
Matt is a bit odd. He likes only certain things. Can you figure out why he likes what he does from the following clues?
- He likes gum, but not mints.
- He likes the beach, but not the ocean.
- He likes cotton, but not wool.
- He likes medicine, but not doctors.
- He likes crystal, but not quartz.
Hot diggity dog
Charmaine is shopping for her big weekend barbecue. Her budget: $100. It costs $4 for a package of ten hot dogs and $3 for a package of eight buns. How many packages of each should she buy to maximize how many hot dogs she can serve? (Hint: She can have extra of either, but she won’t serve a hot dog without a bun.)
Charmaine should buy 13 packages of hot dogs and 16 packages of buns. She will spend exactly $100 and be able to serve 128 hot dogs.
Fill in the blanks
How many common English words (no proper nouns, please) can you make by adding a letter to each of the blanks below? We found five.
Abigail, Oliver, Rosa, and Blake all attend the same summer camp, where they can cook, kayak, rock climb, and zip-line. Each child has a different favorite activity. Can you figure out who likes what best based on the following clues?
- Abigail’s favorite activity isn’t rock climbing.
- Oliver is afraid of heights.
- Rosa can’t do her favorite activity without a harness.
- Blake likes to keep his feet on the ground at all times.
Abigail likes to zip-line, Oliver likes to kayak, Rosa likes to rock climb, and Blake likes to cook.
4321. Moving right, the last digit in the circle becomes the first digit in the next. The other three digits stay in the same order.
Rephrase each item below as a pair of rhyming words. Hint: A phrase’s number is also the number of syllables in each word in the answer.
- A purse from northern Europe
- A manly tortilla chip covered in cheese
- An eatery with a blasé attitude
- A docile teenager
- An association specializing in spontaneity
- Dutch clutch
- Macho nacho
- Nonchalant restaurant
- Acquiescent adolescent
- Improvisation organization
Emma is playing in a field where there are bees buzzing around some flowers. She notices that if one bee lands on each flower, one bee doesn’t get a flower. She also notices that if two bees land on each flower, one flower doesn’t get any bees. How many flowers and bees are there? Also, try out these brain games that will help you get smarter.
Give me five
If all five grids share a common feature, what’s the missing number? Here are some word search puzzles that you can print for free.
In each of the following pairs of words, switch one letter from the first word with one letter from the second word to form pairs of opposites. The switched letters can come from anywhere in either word. If your dog needs a brain boost too, try one of these puzzle toys for dogs.
LOFT / SOUND
COAL / WORM
FAN / REAR
HEAT / FEED
FLESH / STARE
Assuming all the tabs and slots on jigsaw pieces A and B are compatible with each other, how many different ways can you put these two pieces together? If you want a game for the whole family, try these best-reviewed board games.
The names of five different fruits are hidden between consecutive words in the silly story below. Can you find them all?
Example: Washington, DC, and Lima, Peru, are on the same longitude. (melon)
A man goes to a lumberyard. He has little money, so he’s looking for cheap lumber. But the prices are too high. Suddenly feeling really cheeky, the man decides to steal the wood he needs and, like a skilled escape artist, manages to slip away without arousing suspicion. This is why jigsaw puzzles are good for your brain.
Each letter from A to I has one of the nine values listed below. No two letters have the same value. Match each letter to a number to make the equations work.
Kristen’s friends want to buy her a wedding gift. Originally ten friends were going to chip in equally, but then two of them dropped out. Each of the remaining eight friends had to chip in another dollar to bring the total back up to the original amount. How much money did they plan to collect?
3 and 7. In each grid, add the top number to the one in the center to get the number on the left. Then add the center number to the one on the bottom to get the number on the right.
Kangaroo words contain the letters—in order—of another word that means almost the same thing as the original word. For example, the r, e, s, and t from respite form rest. Find the kangaroo words in the terms below.
George, William, John, Abe, and Millard have their birthdays on consecutive days. This year, all their birthdays land between Monday and Friday. Can you figure out whose birthday is on each weekday?
- George’s birthday is as many days before Millard’s as William’s is after Abe’s.
- John is two days older than Abe.
- Millard’s birthday is on Thursday.
Monday: John; Tuesday: George; Wednesday: Abe; Thursday: Millard; Friday: William.
Each of the symbols in this diagram represents a door that is closed but unlocked. When you open a door, all the other doors with the same symbol become locked and cannot be passed through. Can you get from one side of the maze to the other?
Mix it up
An anagram is a word or phrase created by rearranging the letters of a word or phrase into a new term. We call the ones below super-anagrams because the mixed-up phrase creates a loose definition of the original. For instance, “acts phony” and “sycophant.” Can you figure out the super-anagrams for these terms?
- Moon starer
- Bad credit
- Bag manager
- Debit card
- Garbage man
4. The number at the center of each triangle is equal to the sum of the numbers at its base multiplied by the number at its apex. For example, (8 + 3) x 2 = 22.
Mary needs to bring a fruit salad to the annual holiday party, but some of her friends are very picky eaters. Based on her shopping list below, can you figure out what type of fruit they like?
Mary bought a banana, not a strawberry.
Mary bought a kiwi, not a pear.
Mary bought an apple, not an apricot.
Mary bought an orange, not a peach.
Mary bought a mango, not a grapefruit.
Place a number from 1 to 9 in each empty cell of this square so that each row, each column, and both main diagonals add up to the same sum. (You must determine this sum.) The same number can appear more than once.
Tom resolved to get in shape by doing push-ups every morning before work. Each day from Monday to Friday, he did ten more push-ups than he’d done the day before. If Tom did 50 push-ups on Thursday, how many push-ups did he do in total from Monday to Friday?
There are 12 checkers on a table, arranged as shown. Four adjacent checkers can be united in a square. Including the one outlined, how many possible groupings are there of four checkers that form a square?
Rearrange the shapes into a new sequence that follows these rules:
- The triangle is to the immediate left of the pentagon.
- The circle is to the left of the square and to the right of the triangle.
- The octagon is not the last figure in the sequence.
- No shape remains in its original position.
To boost your brain more, try these printable crossword puzzles.
840. Each number is found by multiplying the number that corresponds to its step by the number that precedes it.
Bacon or eggs?
Gwen has very particular tastes. Can you figure out the rule behind her culinary preferences?
Gwen likes bacon, but not eggs.
Gwen likes lemon, but not lime.
Gwen likes jelly, but not marmalade.
Gwen likes pasta, but not rice.
Pointing the way
Move the numbers from the outer frame onto the board so they snake together vertically, horizontally, or diagonally in sequence from 1 to 25. (For example, 2 must touch both 1 and 3.) The catch: You can only move a number in the direction indicated on its home square. Each number fits in its own cell.
Timing is everything
Rich lives in the Eastern Standard Time zone. His sister, Barbara, lives in the Central European Time zone, six hours ahead of him. Rich works between 8 a.m. and 5 p.m. in his local time and goes to sleep each evening at 10 p.m. on the dot. Barbara works between 9 a.m. and 6 p.m. and always goes to sleep at 11:30 p.m. in her own local time. Is there any window in which Rich could call Barbara after his workday without interrupting her on the job or disturbing her sleep?
Each letter from A through H has one of the eight values listed below, and no two letters have the same value. Which number goes with which letter to make all the equations true?
2 3 4 5 8 12 13 17
F + A = C
G + B = D
F + D = H
B + H = C
E + G = B
An imperfect fit
Imagine the two-dimensional shape D is fixed in place and sits in a three-sided box. Shapes A, B, and C can be rotated and placed onto D only from above and cannot stick out past the box on the right or left. One of the three cannot be placed onto D without leaving blank space beneath it in the box. Which one?
Twenty times. The digit 5 appears ten times as a last digit (5, 15, 25 … 95) and ten times as a first digit (50, 51, 52 … 59). Check out these word puzzles that will leave you stumped.
The grid contains matches of different sizes, any of which may be completely unburned, partially burned, or completely burned. Matches burn from the head (the red end) to the tail without skipping segments. The numbers outside the grid indicate the number of burned segments in the corresponding row or column. Can you shade in the burned segments to “match” the numbers?
Try these morning brain boosters to keep your mind sharp.
Sophie and Caroline made arrangements to meet at a café at 2 p.m. Sophie thinks her watch is 25 minutes fast, although it is actually 10 minutes slow. Caroline thinks her watch is 10 minutes slow, while it is actually 5 minutes fast. What will happen if they both aim to arrive exactly on time?
Sophie will be 35 minutes late. Caroline will arrive at 1:45 p.m., 15 minutes ahead of time. See if you can solve these really tricky brain teasers.
Meteor showers bring spring flowers
Space dust has landed on Earth, carrying with it seeds for exotic new alien flowers. One of them still lacks a name. If the xenobotanists follow the same rules they used to create the other terms, what should they call the last flower?
Only the smartest people can solve these detective riddles.
The long and short of it
Six neighborhood children—Leisha, Benito, Delia, Charlotte, Weldon, and Zina—were measured yesterday. Weldon is taller than Delia but shorter than Zina. Leisha is taller than Benito but shorter than Delia and Weldon. Benito is not the shortest. List the kids in order of height from tallest to shortest.
A whole number between one and seven belongs in each of the seven bubbles. Each number occurs once. The sums of some of the numbers are revealed in the areas where their bubbles overlap. Can you figure out which number goes in each bubble?
Test your numbers knowledge with these math riddles.
None of the white squares in this diagram have their edges lined up. One of the squares is a different size from the others. Can you find it?
These are the toughest riddles ever. Can you solve them?
Carmela receives a text message from an unfamiliar number, so she texts back, “Who is this?”
The strange response: “It’s one of your female relatives. Your mother’s mother is my father’s mother-in-law.” Even assuming that this information is true, it doesn’t help Carmela pinpoint an individual, since there are two relationships it could describe. What are they?
Complete the grid so that each row, each column, and each three-by-three frame contains the nine letters from the black box at the top. The hidden nine-letter word is in the diagonal from top left to bottom right.
Only 2 percent of people can solve Einstein’s Riddle. See if you can beat it!
More or less
Place the hexagons below into the pyramid so each number is either greater than the sum of the two numbers below it or less than the difference between them. For instance, if two adjacent numbers were 20 and 50, any number higher than 70 or lower than 30 could be on top of them. (And no, do not turn 98 upside down to make it 86!)
If you can solve the secret word in this logic puzzle you might be a genius.
Kate and Faizal both believe that they need a cup of coffee every three hours to stay awake and function. They both drink their first cup at 8 a.m. and another one every three hours thereafter until they go to sleep. Considering the following facts, who is spending more on coffee each week?
- Kate stays up until 10 p.m. Sunday through Thursday and until midnight on Friday and Saturday. Faizal stays up until 10 p.m. every day.
- Kate pays $3 per cup of coffee. Faizal drinks higher-grade organic coffee and pays $4 per cup.
Faizal. He spends $140 per week, while Kate spends $111. See if you can find the doll hidden in this picture.
You just bought nine beautiful lakeside campsites, which you can rent to campers with tents for $20 per campsite per night. You can also upgrade the sites with electrical hookups. This will cost you $60 per campsite but will allow you to rent to RVers for $40 per night. Suppose you can always fill your campground to capacity. If you’re starting without any cash on hand, how many nights will pass before you’ll be able to upgrade all nine sites?
Three. On the first night, you’ll host nine tents and make $180, which you’ll use to upgrade three sites. On the second night, you’ll host three RVs and six tents, earning $240, letting you upgrade another four sites. On the third night, you’ll host seven RVs and two tents, earning you more than enough to upgrade the last two.
Place one of the four basic arithmetic operations (+, –, ×, ÷) in each box to make a correct equation. All operations are performed from left to right, ignoring the mathematical order of operations. The result at each step must be a positive whole number. What’s the equation?
Spade. Each suit has a numerical value: diamonds equal one, hearts equal two, spades equal three, and clubs equal four. Or, if you prefer, diamonds equal four, hearts equal three, spades equal two, and clubs equal one. Either way, each row and column adds up to ten, and the missing symbol is a spade.
How many pets live in my house if all of them are snakes except two, all are hamsters except two, and all are rabbits except two?
Win or lose
The Reds, the Grays, the Blues, and the Blacks have a round-robin tournament wherein each team plays each other team once, for a total of six games. The Blacks won more games than the Blues, and the Grays lost more games than the Blues. The Reds tied the Blacks, the only tie in the tournament (a tie counts as neither a win nor a loss). Who won the game of the Reds versus the Blues?
The Reds. The Blacks tied one game, so they won a maximum of two games. They won more than the Blues, so the Blues won a maximum of one game. Since the Grays lost more times than the Blues, the Grays must have lost all three matches. The match that the Blues won must have been against the Grays, so the Blues lost the match against the Reds. Can you find the missing number in this puzzle?
See if you can spot the difference between these nearly identical animals.
Lois and Helen, widowed sisters, lived together out in the country. Their habits never changed: up at dawn, breakfast, some housework and gardening until lunch. In the afternoon, Helen napped while Lois watched her shows—Helen never watched TV. Then Helen would clean the vegetables for dinner and Lois would cook. In the evening, they’d read before bed. One night before they turned in, a storm knocked out the power. Everything was pitch-black, and Lois began to panic. “What should we do?” she cried. Helen just smiled and kept reading. Why did Helen stay calm while her sister did not?
Jake loves steak; Trish loves fish
Jacob enjoys steak so much that the probability that he’ll have it for dinner on any given evening is one in three. The favorite dish of his wife, Patricia, is fresh fish. The probability that she’ll have it for dinner on any given evening is one in two. Because Jacob and Patricia always dine together, they’ll never have steak and fish on the same night. On average, how many times in a 30-day month will they be having either steak or fish?
Tamara has $20,000 saved up. If four-fifths of what Tamara has equals eight-ninths of what Martina has, how much money does Martina have?
Each letter from A through H has one of the eight values listed below, and no two letters have the same value. Which number goes with which letter to make all the equations true?
Jerry Mander strikes again
Your name is Jerry Mander, and you must draw your town’s voting districts so that George Greene becomes dogcatcher rather than Barbara Blue. To do that, Greene must win the majority of the city’s five voting districts. Each district comprises three households. This map shows how each of the town’s 15 households will vote (the tree represents a park that’s not in any district). The catch: The three households in each district must share at least one border with at least one other household in the district. Can you draw the five districts in a way that guarantees Greene defeats Blue?
Next, try your hand at some of the most famous riddles in history.
Place one of the four arithmetic operations (+, –, ×, ÷) in each box to make a correct equation. All operations are performed from left to right, ignoring the mathematical order of operations. The result at each step must be a positive whole number.
Have a chocolate
Dad: “Where are the chocolate bars I bought?”
Daughter: “I gave half of them to Mom and half of a bar to my little brother. Then I gave half of what was left to Grandma and half of a bar to my little sister. That left me with one bar, which I gladly ate myself.”
How many bars did Dad originally buy?
Try to spot the difference in these ten pictures. It’s really tricky, hopefully, you have a good eye.
There goes the neighborhood
Each of the six people quoted below lives in one of the six houses in the neighborhood shown. The houses are white, brown, green, blue, yellow, and orange. Assuming that everyone is telling the truth, whose house is painted which color?
Mrs. Antonini: Mrs. Borden lives due north of me.
Mrs. Borden: I live in the orange house. I can walk to Mrs. Englehardt’s house without crossing any streets.
Mr. Cruz: I live due east of a green house.
Miss Dubois: There’s a white house north of mine, but I can’t see it from my house, because there’s a brown house in the way.
Mrs. Englehardt: I live directly across a street from both a yellow house and a white house.
Mr. Fung: I live in the green house.
Erik bought some identical brass buttons for a jacket, each for the same price. It just so happens that if you add two to the number of buttons he bought, you get the price of each button in cents. If he spent a total of $4.83, how many buttons did he buy?
You need to acquire at least six pencils, six pens, and six erasers for $5.20 or less. If the packages listed below are the only combinations that are available, which do you take? You can buy more than one of the same package.
A. Two erasers for 70 cents
B. Four pencils, one pen, and two erasers for $1.30
C. Three pencils, four pens, and three erasers for $3.20
D. One pencil, three pens, and two erasers for $1.90
E. One pencil and five pens for $2.30
Using all the letters listed below only once, can you find the names of three spices?
Insert the letters A to K, one per square, so that no two letters in consecutive alphabetical order touch, not even at a corner. Five letters have been placed to get you started.
Can you pass the world’s shortest IQ test? It’s really hard, less than 20 percent of people can.
You need to empty the contents of two of the five boxes listed below into a bag. Which two will give you the best chance of drawing a red ball at random from the bag?
Box A: 3 red balls, 5 silver balls
Box B: 4 red, 6 silver
Box C: 7 red, 9 silver
Box D: 1 red
Box E: 12 red, 14 silver
Francesca is as old as the combined ages of her brothers, Harry and Ernie. Harry is two years younger than Ernie. When everyone was a year younger, the combined ages of the three siblings was three quarters of the sum of their present ages. How old is each sibling now?
Replace the B in the first word with an R and the S in the second word with an H for rush hour.
There are eight semiprecious gems in Ellen’s collection. At current market prices, four are worth $5, three are worth $10, and one is worth $25. She gives them to her three children: Matthew, Aaron, and Jeremy.
The total value of each child’s gift is the same.
Jeremy receives exactly three stones.
Matthew receives the lowest number of stones.
How are the gems distributed?
Under the same flag
On the top are the names of five boats that belong to the same company. Which one of the five names on the bottom would fit in with the rest?
The top names contain a Roman numeral and a number that matches its value, so NAXIR 11 fits in with them.
Party at Charlie’s
You’ve been invited to a party at Charlie’s house. As part of the fun, you’ve agreed to solve a puzzle to figure out where he lives. He has seven friends who live nearby. They’ve given you a map showing all of their houses and Charlie’s house, along with the following information:
Daniel: I can’t see Benita’s house, because Greta’s house is in the way.
Adam: I live directly (not diagonally) across the street from Daniel.
Benita: Elena lives due west of me.
Elena: I have to cross three streets to walk to Franco’s house.
Hal: I live east of Benita.
Where does Charlie live?
You own a toy-making studio with two employees.
Carving a toy takes two hours. Painting one takes one hour. Packaging one takes one hour.
You can’t paint a toy until it has been carved. Similarly, you can’t package one until it has been painted.
Both of your employees are capable of doing any of the three tasks, but they can’t both work on the same task for the same toy at the same time.
What is the lowest number of hours it would take your employees to carve, paint, and package three toys?
Each of these words contains the letters—in order—of another word that means almost the same thing as the original word. For example, the u, s, e, and d from accustomed form the word used. Can you figure them out?
Runs in the family
Tim and his daughter, Carol, both ran in a 10K race. Tim finished in 49 minutes; Carol, in 54. Tim ran at a perfectly steady pace, but Carol lost steam and took exactly 25 percent more time to complete the second half of the race compared with the first. Tim’s wife and Carol’s mother, Marcie, stood at the halfway mark to cheer them on as they passed. Who went by her first?
Forest for the trees
A spanning tree (or just a tree, for short) is a diagram made of dots and straight lines, in which every line goes between two dots, all the dots are connected, and no lines connect with others to form closed loops. Some examples are in the image above.
A drawing that has several spanning trees is called a forest. If a forest has three trees and 27 lines in it, how many dots does it have?
30 dots. Any tree you draw will contain one dot more than its number of lines. So add three (the number of trees in the forest) to 27 (the number of lines). Now, try these word puzzles that will leave you stumped.
Four in a row
In this bird’s-eye view, each of the nested squares represents a stack of four blocks, with smaller ones sitting on top of larger ones. Can you find a line of four blocks in the same row, column, or long diagonal that are all the same color? The line must be straight in three dimensions, meaning it spans blocks sitting at adjacent heights, going from smallest to largest (or vice versa), or at the same height.
In the “ladder” of words below, one letter changes between consecutive rungs. The red blanks indicate which letter changes as you move from one rung down to the next. Can you fill in the words using the definitions given—and the one letter we placed for you?
In a curious little town, Prognostication Peyton (the local groundhog) declares if there will be six more weeks of winter. But Peyton doesn’t make his judgment based on whether he can see his shadow. He makes his call based on his dream from the previous night.
- If Peyton has a good dream the night before Groundhog Day, there’s a 70 percent chance he will declare an earlier start to spring.
- But if Peyton has a bad dream the night before, there’s a 70 percent chance he will declare six more weeks of winter.
Assuming half of his dreams are good and the other half are bad, what’s the overall likelihood that Peyton will declare six more weeks of winter?
A. From left to right, the number of sides on the outer shape decreases by two, the number on the middle shape increases by one, and the inner shape alternates between an octagon and a pentagon.
Great minds love games
Doing a crossword or a Sudoku every day to keep your mind sharp may seem like a recent concept. In fact, people have been challenging their brains with puzzles as far back as 3,600 years ago, when the ancient Egyptians developed math problems on papyrus and wooden tablets. Want more puzzles? Our Mind Stretchers books are available online and wherever books are sold.