There are a number of books on a shelf. If one book is the 4th from the left and 6th from the right, how many books are on the shelf?

using four eights (8) and a one (1) and one mathematical symbol , create the number 100

What is the word or phrase?

A finger goes in me. You fiddle with me when you're bored. The best man always has me first. What am I?

There are four 3-link chains. All you have to do is join them into a big 12-link chain. For joining two closed links, one of the links must be cut and placed onto the other link for closing.

How many minimum links will you have to cut to make the big chain?

Prove that the below maths equation is true.

8 + 8 = 91

If,

20 % 5 = 24

21 % 7 = 33

42 % 6 = 67

Then;

66 % 6 = ?

What does the following represent?

N N N N N N N

A A A A A A A

C C C C C C C

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

You can use any mathematical symbols in the space provided to make all above algebraic expressions true.

Two boys were admitted to a school. When the headmaster asks them about their parents, they tell him that they have same parents (father and mother). On further inquiry, it turns out that they both share the same date for their birthday.

"Are you twins," ask the headmaster.
"No," replies the boys.

Is it possible?