I am white when I am dirty, and black when I am clean. What am I?

In the picture given below, can you find out which digit will take place of the question mark?

No matter how little or how much you use me, you change me every month. What am I?

Find three whole, positive numbers that have the same answer when multiplied together as when added together.

A container contains 100 eggs. They can be either fresh or rotten. What is sure is the fact that there is at least one fresh egg in that container.

If you are asked to pick two eggs randomly from the container, at least one of them will be rotten.

Can you calculate how many eggs in that container are fresh?

I have branches, but no fruit, trunk or leaves. What am I?

Nine marbles are arranged in the image below. Can you slide two marbles to form a square?

A wooden log balances equally on the scales when weighed with three-quarters of a pound and three-quarters of a wooden log.

Can you calculate the weight of the entire wooden log?

Make eight squares by moving only two matchsticks.
Note- Square can be of different sizes.

2, 3, 5, 9, 17, _ What is the next number in the sequence?