Can you find the key in the picture below?

Rectify the following equality 101 - 102 = 1 by moving just one digit.

I come in different shapes and sizes.
Parts of me are curved, other parts are straight.
You can put me anywhere you like,
but there is only one right place for me.
What am I?

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

Can you find out the remainder when 3^300 is divided by 5?

There are nine letters in the below-given diagram. You have to form a nine-letter word using these letters.

If nine thousand, nine hundred nine dollars is written as $9,909,
how should twelve thousand, twelve hundred twelve dollars be written?

You visit a home for specially-abled children on the occasion of Christmas where you meet with 50 children. You have a box of chocolates containing 50 chocolates exactly.

What if you were asked to one chocolate to each child in a manner that one chocolate still remains in the box? Is it possible?

Can you find a five letter word that is left with only two letters if one is removed?

Find the next number in the series

12, 20, 40, 72, 116, 172 ?