What does below rebus means ?

They came out at night, without being called.
They lost at day, without being stolen.
Who are they?

Can you place six X (crosses) in below board without making three in a row in any way ?

I have two sand hourglasses:
1. A 7 minute one and
2. An 11-minute one.

Using just these 2 sand hourglasses, how can I measure time as 15 minutes?

What happened when the wheel was invented?

You have a three-gallon and a five-gallon measuring device. You wish to measure out four gallons.

Can you count the number of matches in the picture below ?

A 3 digit number is such that it's unit digit is equal to the product of the other two digits which are prime. Also, the difference between it's reverse and itself is 396.

What is the sum of the three digits?

Can you solve the tricky chess rebus puzzle below by ciphering the hidden meaning?

Decode this picture on T-Shirt and tell what it says ?