Why is it very easy to weigh a fish?

Can you find the missing letter in the sequence?
S - T - I - L - ? - T - F - Y - C

An ape is trying to climb on a pole that is 60 feet high. Due to the slippery surface, the ape climbs 3 feet in a minute only to slip back 2 feet.

How much time do you think the monkey will take to reach the top of the pole?

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

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?

Rumel, A detective who was mere days from cracking an international smuggling ring has suddenly gone missing. While inspecting his last-known location, you find a note:

710 57735 34 5508 51 7718

Currently, there are 3 suspects: Bill, John, and Todd. Can you break the detective's code and find the criminal's name?

A mile-long train is moving at sixty miles an hour when it reaches a mile-long tunnel. How long does it take the entire train to pass through the tunnel?

I am weightless, but you can see me. Put me in a bucket, and I'll make it lighter. What am I?

There are 20 people in an empty, square room. Each person has full sight of the entire room and everyone in it without turning his head or body, or moving in any way (other than the eyes). Where can you place an apple so that all but one person can see it?

I look at you, you look at me I raise my right, you raise your left. What am I?