I am the one who remains awake when you sleep. But I need to rest when you awake. Who Am I?

Find out the missing number in the picture attached:

You are playing a game with your friend Jack. There are digits from 1 to 9. You both will take turn erasing one digit and adding it to your score. The first one to score 15 points will win the game.

Would you want to play first or second?

PS: The sum should be exactly 15.

If you drop me I’m sure to crack, but give me a smile and I’ll always smile back. What am I?

If a zookeeper had 100 pairs of animals in her zoo, and two pairs of babies are born for each one of the original animals, then (sadly) 23 animals don’t survive, how many animals do you have left in total?

Use only one mathematical symbol and all numbers (0-9) to get a sum of 99

Consider all the numbers between 1 and 1 million. Among all these numbers, there is something very special about the number 8 and the number 2202. What is it?

How will you measure 15 minutes using two hourglasses of 7 minutes and 11 minutes respectively?

Can you find out which number multiplied by itself will give the output as 12345678987654321?

Find the hidden tiger in the given optical illusion ?