Eight of us go fourth, not back, to protect our king from an attack. What are we?

What is the end of everything?

Prove that the below maths equation is true.

8 + 8 = 91

Prove that twice of ten is the same as twice of eleven.

When I get multiplied by any number, the sum of the figures in the product is always me. What am I?

Can you find the missing piece of the Porsche?

Can you find the missing number in the third row?
35 20 14
27 12 18
5 2 ?

How many people must be gathered together in a room, before you can be certain that there is a greater than 50/50 chance that at least two of them have the same birthday?

Can you find the least possible number such that

If the number is divided by 3, it gives the remainder of 1;
If the number is divided by 4, it gives the remainder of 2;
If the number is divided by 5, it gives the remainder of 3;
If the number is divided by 6, it gives the remainder of 4.

When Jack was six years old he hammered a nail into his favourite tree to mark his height. Ten years later at age sixteen, Jack returned to see how much higher the nail was. If the tree grew by five centimetres each year, how much higher would the nail be?