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24 Brain Games Guaranteed to Boost Your Brain Power

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!

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Marcel Danesi

Counting Digits

How many times does the 
digit 5 occur in the numbers from 1 to 100?

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Marcel Danesi


Twenty times. The digit 
5 appears 10 times as a last digit (5, 15, 25 … 95) and 
10 times as a first digit 
(50, 51, 52 … 59).

Check out these crossword puzzle clues that’ll leave you stumped.

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Marcel Danesi

Match Play

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?

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Fraser Simpson


Try these natural concentration boosters to keep your mind sharp.

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Marcel Danesi

Lost Time

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?

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Marcel Danesi


Sophie will be 35 minutes late. Caroline will arrive at 1:45 p.m., 15 minutes ahead of time.

This is why your brain never wants you to exercise.

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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?

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Cosmofilium jupibristo. The first half of the top term tells the colour of the flower’s centre; the last half is the petal colour. The first half of the bottom term tells the shape of the flower’s centre; the last half is the shape of the petals.

Reading in this font could improve your memory.

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Quick Crossword

Place the words listed below
in the crossword grid.

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Only the smartest people can solve these math riddles.

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Marcel Danesi; illustration: iStock

The Long and 
Short of It

Six neighbourhood 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.

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Marcel Danesi


Zina, Weldon, Delia, 
Leisha, Benito, Charlotte.

This is one of the best things you can do to ward off memory loss.

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Roderick Kimball

Bubble Math

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?

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Darren Rigby


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?

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Marcel Danesi

Family Relations

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?

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Marcel Danesi


Sister or first 

Don’t miss these everyday habits of people with impressive memory.

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Word Sudoku

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.

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Darren Rigby

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!)

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Coffee Addicts

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.

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Faizal. He spends 
$140 per week, while 
Kate spends $111.

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Happy Campers Puzzle

Happy campers

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?

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Happy Campers Answer


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.

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Arithme-pick PuzzleFraser Simpson


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?

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Arithme-pick Answer


5 + 7 ÷ 3 × 9 – 4 = 32

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Suit Yourself PuzzleFraser Simpson

Suit yourself

The playing card suits in the cells above are placed according to a pattern. What’s the missing symbol?

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Suit Yourself Answer


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.

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Animal House PuzzleMarcel Danesi

Animal house

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?

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Animal House Answer


One of each, for a total 
of three.

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Win or Lose PuzzleDarren Rigby

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?

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Win or Lose Answer


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.

An MIT professor called this “the hardest logic puzzle ever.”

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Quick Crossword Puzzle

Quick crossword

Place the words listed below in the crossword grid.

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Quick Crossword Answer


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100-Word Mystery Puzzle

100-word mystery

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?

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100-Word Mystery Answer


Helen was blind.

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Jake Loves Steak; Trish Loves Fish PuzzleSamantha Rideout

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 
favourite 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?

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Changelings Puzzle


Each of the three lines of letters below spells the name of a fruit, but four letters from the first word are in the third line, four letters from the third word are in the second line, and four letters from the second word are in the first line. What are the words?

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Changelings Answer



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Net Worth PuzzleMarcel Danesi

Net Worth

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?

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Sum-Thing SpecialFraser Simpson

Sum-Thing Special

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?

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Sum-Thing Special Answer


A = 6, b = 13, c = 1, d = 7, 
e = 16, f = 3, g = 5, h = 10

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Jerry Mander Strikes Again PuzzleRoderick Kimball of Enigami Fun

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?

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Jerry Mander PuzzleRoderick Kimball of Enigami Fun


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.

Next, try your hand at some of the most famous riddles in history!

Originally Published in Reader's Digest