What has six faces, but does not wear makeup, has twenty-one eyes, but cannot see? What is it?

The centre of the third figure is empty. What digit should fit inside?

What's the only room from which no one can enter or leave

A famous swimmer can swim downstream in a lake in exactly 40 minutes with the lake current.
He can swim upstream in that lake in exactly 60 minutes against the lake current.
The length of the lake is 2 km.

How long he can cover the distance of one side at a still lake with no current?

How can you tell a raw egg from a hard-boiled egg?

Can you find out the missing number?

? 4 5 3 5

9 5 7 10 3

We have arranged an array of numbers below. What you have to do is use any kind of mathematical symbol you know excluding any symbol that contains a number like cube root. You can use any amount of symbols but you have to come up with a valid equation for all of them.

0 0 0 = 6
1 1 1 = 6
2 + 2 + 2 = 6
3 3 3 = 6
4 4 4 = 6
5 5 5 = 6
6 6 6 = 6
7 7 7 = 6
8 8 8 = 6
9 9 9 = 6

what's the probability of getting a king or a queen from a pack of 52 cards?

Name a key which is hardest to turn.

I have 50 feet long of cloth, I need to create 50 handkerchiefs each size of 1 foot. I take one minute to cut a 1-foot handkerchief. So how long will it take to cut 50 handkerchiefs?