Take away the whole and some still remain. What is it?

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?

Can you move 2 matchsticks to form four equal sized squares.

What jumps when it walks and sits when it stands?

Why did Navjot Singh Sidhu put the new January calendar in the freezer

There is a barrel with no lid and some wine in it. 'This barrel of wine is more than half full,' said Curly. 'No it's not,' says Mo. 'It's less than half full.' Without any measuring implements and without removing any wine from the barrel, how can they easily determine who is correct?

Can you name an animal whose killing cannot be performed without spilling your own blood?

Replace the question mark with the correct number, given the pair of numbers exhibits a similar relationship?

? : 3839 :: 11 : 1209

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

Why Aeroplane windows are round?