One is to three as three is to five and five is to four and four is the magic number.
What is the pattern?

I cannot talk, but I always reply when spoken to. What am I?

Where do fish keep their money?

A man has a barrel filled with oil that weighs 100 pounds, and then he puts something into it. Now the barrel weighs less than 100 pounds. What did he put in the barrel?

What number comes next in this sequence:
7 8 5 5 3 4 4 _

What is so fragile that saying its name breaks it?

Different lights make me strange by changing me into different sizes. What am I?

In my garden, I have many trees but only one of them is the mango tree. In these mango trees, there are some mangoes(as expected).

But after a strong wind, there are neither mangoes on the tree nor on the ground. Explain?

Four people need to cross a rickety bridge at night. Unfortunately, they have only one torch and the bridge is too dangerous to cross without one. The bridge is only strong enough to support two people at a time. Not all people take the same time to cross the bridge. Times for each person: 1 min, 2 mins, 7 mins and 10 mins. What is the shortest time needed for all four of them to cross the bridge?

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

which number am I?