# MATH BRAIN TEASERS

### Fun Facts (Hints)

Mathematics has an extensive history in just about every culture or civilized society known to man. Listed below are some cool facts to get those math juices flowing:
• In 1852 mathematician JJ Sylvester established the "theory of algebraic invariants."
• In 1995 math great Andrew Wiles, proved "Fermat's Last Theorem."
• The first decimal number system is said to have been invented in Ancient Egypt around 5000BC.
• The Ancient Mayan civilization located in Central America is one of the only cultures in the recorded history of the world to use a place-value number system.
• The American Mathematical Society was formed in the late months of 1888 in New York.

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Math brain teasers are awesome math questions and problems given to entertain us while at the same time giving us an education. Cognitive skills are vital to performing well in almost every activity that we participate in daily, especially in the math field.

This collection compiled by our staff on a regular basis will provide you with a great way to workout that math brain power, and will hopefully benefit you in your studies.

This is an awesome collection for anyone ages 5 and up, and contains a comprehensive set of riddles related to math for a wide range of audiences.

How many of these convoluted math riddles do you think that you can solve? Try out our collection, and be sure to come back regularly to solve our newly added math brain teasers.

## 20 Plus 20 Plus 20 Riddle

Hint:
Use the number 5 three times, 55 + 5 = 60
Did you answer this riddle correctly?
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Solved: 38%

## 12 Islanders Teeter Totter Riddle

Hint:
Six on one side - six on the other = one side is heavier.

Take the heavier six men, divide them into three and three (random).

Three on one side - three on the other = one side will one heavier.

Divide that three men from the heavier side side, have one on one side - one on the other.

Two results can determine which of the last three men weight is a different weight than each other.

With the last group of three men, have two men go head-to-head. The see-saw will either weight different: one weights more than the other man meaning the heavier man is the "12th man" or the see-saw will balance between the two men because they are the same weight. That means the third man standing on the sidelines by default weights more than the last two men weighted. Thus making that man on the sidelines the "12th man" that weights more than other 11.

Heavier wins 6v6; winner gets divided. Heavier wins 3v3; winner gets divided. Heavier wins 1v1 (12th man) or Equal 1v1 = third man weight more, he's the 12th man.

You could find the same results changing the process and picking from the lighter group three times. You’re only trying to find the difference in weight. Not the exact weight (more or less) of that "12th man."

Lightest 6v6; Lightest 3v3; Lightest 1v1 or Equal 1v1 = third man weight less.
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Solved: 62%

Hint:
If you said 5000 you're wrong! The answer is 4100, how?

1000 + 40 = 1040
1040 + 1000 + 30 = 2070
2070 + 1000 + 20 = 3090
3090 + 1000 = 4090
4090 + 10 = 4100
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Solved: 58%

## 17 Cows Riddle

Hint:
The neighbour borrowed an extra cow, to make the total number of cows 18. Then the oldest son got 1/2 of 18 is 9 cows, the middle son got 1/3 of 18 is 6 cows, and the youngest son got 1/9 of 18 is 2 cows. Since 9+6+2 = 17, the cows could be divided among the three brothers in such a way that the borrowed cow was left over, and could be returned to its owner.
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Solved: 64%

## 12 = 6 And 6 = 3 Riddle

Hint:
12 (Twelve) has 6 letters,

6 (Six) has 3

Therefore,

10 (Ten) will be equal to 3
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Solved: 47%

## Borrow \$50 From Mom And \$50 From Dad Riddle

Hint:
Total Money taken = \$100(\$50+\$50)

Now,

Bag's Price = \$ 97

Remaining Amount = \$100 - \$97

= \$ 3

Returned = \$ 1 + \$ 1

=\$2

In pocket = \$1

Total money owed = \$100- ( Returned amount)

= \$98( Bag's amount and reserved amount)

So, it was a calculation mistake.
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Solved: 52%

## The Correct Number Riddle

Hint:
121

Explanation
Tables consist of squares of the number from 4 to 12.
11^2 = 121.
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Solved: 56%

## Steals \$100 Riddle

Hint:
The loss is \$100.
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Solved: 65%

## Shoe Man Whistle

Hint:
The third equation has a term with a pair of whistles. The last line involves a single whistle.

Furthermore, the man in the second and third lines are wearing a whistle, but the man in the last line is not wearing a whistle. Presumably the value of the whistle should be accounted for to get the correct answer.

The pictures can be translated into the following equations:

shoes + shoes + shoes = 30
shoes + (man + whistle) + (man + whistle) = 20
(man + whistle) + 2(whistles) + 2(whistles) = 13
shoes + (man) x (whistle) = ?

From the first equation we can solve for the shoes value:

shoes + shoes + shoes = 30
3(shoes) = 30
shoes = 10

We can then solve the second equation for the (man + whistle) value:

shoes + (man + whistle) + (man + whistle) = 20
10 + 2(man + whistle) = 20
2(man + whistle) = 10
man + whistle = 5

Then we solve the third equation for the whistle:

(man + whistle) + 2(whistles) + 2(whistles) = 13
5 + 4(whistles) = 13
4(whistles) = 8
whistle = 2

We also need to solve for the value of the man:

man + whistle = 5
man + 2 = 5
man = 3

Now we can evaluate the final expression, remembering the order of operations that multiplication should be evaluated before addition:

shoes + (man) x (whistle) = ?

10 + 3 x 2
= 10 + 3 x 2
= 10 + 6
= 16
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Solved: 47%

## \$100 Bill Grocery Store Thief

Hint:
The best answer from the choices is the owner lost \$100. The \$100 bill that was stolen was then given back to the owner. What the owner loses is the \$70 worth of goods and the \$30 in change, which makes for a total of \$70 + \$30 = \$100. The owner has lost \$100.

Technically, the owner lost \$30 plus the value, V, of the \$70 of goods. Since stores typically sell goods at a markup, the value may be less than \$70. But in the case of a loss leader, the owner may have lost more than \$70.
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Solved: 73%

## Banana Clock Riddle

Hint: 1. Look closely at the clock. 2. Number of Bananas. 3. Some thing regarding the sides of the Shapes figure.
38

Logic :
From 1st the hexagon shape has value 15.
The shape has 15 edges(6 of hexagon,5 of Pentagon and 4 of Square)
From 2nd we get value of one bunch of bananas is 4.
So each banana has value of 1.
From 3rd we get that each clock has value of 3.
Which resembles the time on the clock which is 3.
Hence by using these insights, we get the last required values as
Clock = 2 (2 in the clock)
Bananas = 3 (3 bananas in the bunch)
Hexagon = 11 (Hexagon[6 sides] and pentagon[5 sides], so 6+5=11)
So required value is
2+3+3x11=?
2+3+33=? (Multiply first - Bodmas rule)
5+33=38 and hence the answer is 38.
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## Age Of Three Daughters Riddles

Hint:
3, 3, and 8. The only groups of 3 factors of 72 to have non-unique sums are 2 6 6 and 3 3 8 (with a sum of 14). The rest have unique sums:

2 + 2 + 18 = 22
2 + 3 + 12 = 18
2 + 4 + 9 = 15
3 + 4 + 6 = 13

The house number alone would have identified any of these groups. Since more information was required, we know the sum left the answer unknown. The presence of a single oldest child eliminates 2 6 6, leaving 3 3 8 as the only possible answer.
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Solved: 48%

## Bus Driver Riddle

Hint:
You are.
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Solved: 75%

## Pearl Problems Riddle

Hint: If you took out 2 pearls, you would have about a 50% chance of getting 2 gold bars. However, you can take even more pearls and still retain the 50% chance.
Take out 5000 pearls. If the remaining pearl is white, then you've won 5000 gold bars!
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## Coconut Toll Booth Riddle

Hint:
1 10
2 10
3 9
4 9
5 9
6 8
7 8
8 7
9 7
10 7

200-84 = 116
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Solved: 63%

## Post Your Math Brain Teasers Below

Can you come up with a cool, funny or clever Math Brain Teasers of your own? Post it below (without the answer) to see if you can stump our users.