When monkey rotate the gear, which mark will be hit 1 or 2 ?

Why do we preferably have round manhole covers and not square ones?

A girl has as many brothers as sisters, but each brother has only half as many brothers as sisters. How many brothers and sisters are there in the family?

I speak without a mouth, and hear without ears. I have no-body, but I come alive with the wind. What am I?

Can you count the number of triangles in the given figure?

What work can one never finish?

Can you solve this tricky maths equation problem by replacing it? mark with the correct symbol?

19834 -----: 187
15921 -----: 153
17561 -----: 139
13734 -----: ???

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?

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?

When can we add 2 to 11 and get 1 as the correct answer?