# 100+ Challenging math riddles to keep your mind sharp #### Count the triangles - Math Riddle

###### 91.Math Riddles

How many triangles can you count in this shape? • A.7
• B.8
• C.9
• D.10
C.9
• `Explanation :  Count the triangle carefully without leaving any triangle inside`

#### Number Math Riddle with answer

###### 92.Math Riddles

Can you solve this number ? • A.1
• B.4
• C.3
• D.6
B.4
• `Explanation :  there are four intersecting points.`

#### Complete the sequence - Math Riddle

###### 94.Math Riddles

1=3, 2=3, 3=5, 4=4, 5=4, 6=3, 7=5, 8=5, 9=4, 10=3, 11=? 12=? Can you complete the sequence?

• `6`
`Explanation :  6. The numbers present represents the number of letters in the spelling of its corresponding number.`

#### 500 eggs in 500 minutes - Math Riddle

###### 95.Math Riddles

Two hens can lay two eggs in two minutes. If this is the maximum speed possible, what is the total number of hen needed to get 500 eggs in 500 minutes?

• A.2
• B.5
• C.4
• D.10
A.2
• ```Explanation :  Two hens because 2 minute 2 egg
1 minute 1 egg
500 minute 500 eggs```

#### Peter was asked how old he was - Math Riddle

###### 96.Math Riddles

Peter was asked how old he was. His reply was like this; In a period of 2 years my age will be twice my age when you asked this five years ago. How old is he?

• A.10
• B.9
• C.14
• D.12
D.12
• ```Explanation :  Let Peter's age be X Years
X+2=2(X 5)
X+2=2X 10
X=12```

#### 100 coins fell down - Math Riddle

###### 97.Math Riddles

100 coins fell down and got scattered inside a dark place. 90 of the coins fell with heads facing up and the rest 10 coins fell with tails up. You are asked to sort out these coins into 2 piles. However, each pile should have the same count of tails up coins. How is it possible?

• `Firstly, all the piles need not be of same size. I can make 2 piles, one with 90 coins and the other with 10 coins. Now just flip all the 10 coins on the pile. So the piles will have the same count of tails.`

#### Which number replace - Math Riddle

###### 100.Math Riddles

Which number replaces the question mark?

30 6 2 3 2 12 2 ?

• A.40
• B.50
• C.60
• D.30
D.30
• ```Explanation :  As you can see the lower number rows are always bigger than upper row ones with the difference going up by 3 with every step
34 - 32 = 2
32 - 27 = 5 (difference going up by 3 from last difference)
56 - 48 = 8 (difference going up by 3 from last difference)
? - 19 = 11 (difference going up by 3 from last difference)
So ? = 30```

#### Quickfire equation? - Math Riddle

###### 101.Math Riddles

Can you solve the below quickfire equation? • A.+1
• B.-1
• C.2
• D.3
A.+1
• ```Explanation :  Ans  :  +  1
5x^2 = ?25
5x^2 = 5
X^2 = 5/5
X=?1 = +  1```

#### Smiley equation - Math Riddle

###### 102.Math Riddles

Can you solve the below smiley equation? • A.200
• B.150
• C.180
• D.300
C.180
• ```Explanation :  180
30+30+30=90
10+30+10 =50
10+ 15+15=40
30+10*15= 180```

#### Number puzzle - Math Riddle

###### 105.Math Riddles

2 2 = 00 3 3 = 03 4 4 = 08 5 5 = 15 6 6 = 24 7 7 = ??

8 8 2(1+3)= ?

• `35`
```Explanation :  The value of RHS is
(A*A)   (A+A)
i.e(2*2)   (2+2) = 4   4 = 00
(3*3)   (3+3) = 9   6 = 03
(4*4)   (4+4) = 16   8 = 08
(5*5)   (5+5) = 25   10 = 15
(6*6)   (6+6) = 36   12 = 24
(7*7)   (7+7) = 49   14 = 35```