By including only four matchsticks in below picture, you have to make "Four Triangles And Two Squares"

What is in seasons, seconds, centuries and minutes but not in decades, years or days?

Below, you will find the mathematical proof that 10 equals 9.99999?. But is that possible or there is something wrong about it? Can you find the error?

x = 9.999999...
10x = 99.999999...
10x - x = 90
9x = 90
x = 10

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

If you drop a 15 kg iron bar and a 5 kg bag of cotton from a height of 50 meters which will reach the ground first?

All of Jacob's shoes are red except two.
All of Jacob's shoes are green except two.
All of Jacob's shoes are yellow except two.

How many shoes does Jacob have?

Can you place three balls such that the equation shown in the picture holds true?

Who is that with a neck and no head, two arms and no hands? What is it?

The centre of the third figure is empty. What digit should fit inside?

Solve the following series:
AZ, GT, MN, __, YB