What does this mathematical rebus means ?

When can we add 2 to 11 and get 1 as the correct answer?

A girl has as many brothers as sisters, but each brother has only half as many brothers as sisters. How many brothers and sisters are there in the family?

A four-digit number (not beginning with 0) can be represented by ABCD. There is one number such that ABCD=A^B*C^D, where A^B means A raised to the B power. Can you find it?

I am 5 letters long.
My first two tell you who I am
My first 3 could be a medicine
My last three reversed could be a young boy.
My 4th, 3rd and 2nd in that order could be a fruit drink.
If you have me you may hang me round your neck
WHAT AM I ?

John replied, when asked how old he was. In 2 years he will be twice as old as he was five years ago.' How old is he ?

Before Balboa discovered the Pacific Ocean, which was the largest ocean before that?

Replace each alphabet with the number (1-9) to make the below equation correct.

AB * C = DE - F = GH / I

A bomb exploded in a room full of married couples and no one died. How?

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?