What is the word or phrase?

Christina has four daughters, and each of her daughters has a brother. How many children does Christina have?

What brings you down but never up?

A man who was outside in the rain without an umbrella or hat didn’t get a single hair on his head wet. Why?

Most people think of me as money. But when they find me in the water, they won’t get any money out of me. What am I?

A brand new Mobile Phone was on sale at 20% as a promotional offer. By what per cent must the Mobile price be increased to sell it at the original price again?

A boy was locked in a room by some robbers. All that is in the room is a piano, a calendar, and a bed. The room is locked from the outside. What does he eat, drink, and how does he escape and get out?

Before Mount Everest was discovered, what was the highest mountain in the world?

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?

Can you decipher the two rows to find the hidden word?