Find the next number in the series below

21 32 54 87 131 ?

what does the below rebus means?

If nine thousand, nine hundred nine dollars is written as $9,909,
how should twelve thousand, twelve hundred twelve dollars be written?

See the given image carefully. What you have to do is move the blue checkers in the position of the black checkers and vice versa. You are only allowed to move the checker to an adjacent empty space. Do it in the least possible moves.

A clock loses 10 minutes each hour. If the clock is set correctly at noon, what time is it when it reads 3 PM?

How many triangles can you find in this given picture?

What is the fastest way to double your money?

Find the mistake in the below maths equations

A = 2
A(A-1) = 2(A-1)
A2-A = 2A-2
A2-2A = A-2
A(A-2) = A-2
A = 1

Count the number of triangles in the picture below:

A prisoner is told: "If you tell a lie, we will hang you and if you tell the truth, we will shoot you." What did the prisoner say to save himself?