You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

A man died, leaving $10,000,000 for his widow, 5 sons and 4 daughters. Each daughter received an equal amount, each son received twice as much as a daughter, and the widow received three times as much as a son.

How much did the widow receive?

How will you measure 15 minutes using two hourglasses of 7 minutes and 11 minutes respectively?

What has 88 keys?

Things are just as they seem, right? Well, check again.
Can you count the number of tigers in this picture ?

As shown in the image, the nine Dogs are square fenced. By constructing just two square fences can you make sure that two Dogs cannot meet each other without crossing the fence?

A girl rode into a tourist spot out of the city on Thursday. She loved the place and decided to stay for a few days. She stayed for four days and then she left for back home on Thursday.

How can this be possible?

If,

A + B = C
D - C = A
E - B = C

Based on the above equations, find out the answer for:

D + F = ?

Our product and our sum always give the same answer. Who are we?

If you say my name, I will no longer exist. What am I?