What has hands, but can’t clap?

Find out the missing number in the picture attached:

If,

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

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

D + F = ?

How can you leave a room with two legs and return with six legs?

A number with an interesting property:

When I divide it by 2, the remainder is 1.
When I divide it by 3, the remainder is 2.
When I divide it by 4, the remainder is 3.
When I divide it by 5, the remainder is 4.
When I divide it by 6, the remainder is 5.
When I divide it by 7, the remainder is 6.
When I divide it by 8, the remainder is 7.
When I divide it by 9, the remainder is 8.
When I divide it by 10, the remainder is 9.

It's not a small number, but it's not really big, either.
When I looked for a smaller number with this property I couldn't find one.

Can you find it?

Can you decipher the following common phrase?

T M C
A U O
H S M
W T E

Can you write down eight eights so that they add up to one thousand?

What is the largest amount of money that you can possess in change and still if someone asks you for a dollar, you won't be able to give?

A tree doubled in height each year until it reached its maximum height over the course of ten years. How many years did it take for the tree to reach half its maximum height?

Who is that with a neck and no head, two arms and no hands? What is it?