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

Spelt forwards I’m what you do every day, spelled backwards I’m something you hate. What am I?

You are presented with three boxes. One of them has a red ball inside and the other two have a black ball inside each of them. You are asked to pick up the one with red ball and you pick one. Now, one of the other boxes is opened and it is found to have a black ball.

You are presented with a chance to change your box with the one that is left closed. Will you change your box? Why or why not?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

I possess a head

I flaunt a tail

But I don't have mouth or legs

Can you find out who I am?

Can you solve below mathematical equation?

2^1234 - 2^1233

What brings you down but never up?

If it took eight men ten hours to build a wall, how long would it take four men to build it?

Find the next number in the sequence

5 12 24 36 ?

What can you hold in your right hand, but never in your left hand?