Which number should replace the question mark?

Can you find a five letter word that is left with only two letters if one is removed?

Can you make numbers like 24, using numbers 3,3,7 & 7 with any arithmetic operator?

When we see 2 but call 10?

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

We have four gears with below features=> Both Gear A and D has 60 teeth=> Gear B has 40 teeth=> Gear C has 20 teeth=> Every two minutes, Gear B makes 25 full turns.What is the relative speed of Gear A and Gear B?

Once upon a time, there was a castle on a square island. The entire island was surrounded by a 14m wide trench. The Romans had wanted to invade the castle and had brought a few wooden planks along with them to facilitate themselves in crossing the moat. The planks were however found to be only 13m long.

The Romans still managed to cross the trench. How did they do it?

What can go up a chimney down, but can’t go down a chimney up?

Intelligence Agency need to break the vault but the problem is that they are not able to break the vault.

On the vault, a text is written as:

31 11 33 33 43 45
21 25
31 24 11 31 51 41

To Break the code Intelligence Agency brings a mathematician named Joseph.
Minutes later he deciphers the code.

Whats the code?

What has many keys but can’t open a single lock?