Prove that twice of ten is the same as twice of eleven.

What's a single-digit number with no value?

Can you identify the hidden rebus in the image below?

Can you find a pattern and the missing number in the series given below?

100, 155, 258,? , 584, 819.

What does a man do only once in his lifetime, but women do once a year after they are 29?

John is 45 years older than his son Jacob. If you find similarities between their ages, both of their ages contain prime numbers as the digits. Also, John's age is the reverse of Jacob's age.

Can you find their ages?

What is the word or phrase?

John is on an island and there are three crates of fruit that have washed up in front of him. One crate contains only apples. One crate contains only oranges. The other crate contains both apples and oranges.

Each crate is labelled. One reads 'apples', one reads 'oranges', and one reads 'apples and oranges'. He know that NONE of the crates have been labeled correctly - they are all wrong.

If he can only take out and look at just one of the pieces of fruit from just one of the crates, how can he label all of the crates correctly?

Six glasses are in a row. The first three are filled with milk and the last three are empty. By moving only one glass, can you arrange them so that the full and the empty glasses alternate?

If six children and two dogs were under an umbrella, how come none of them got wet?