Find the next number in the series below

21 32 54 87 131 ?

Solve the equation by replacing the alphabet with numbers.

MOM + MOM + NO = BOOK=

You have a thousand Re. 1 coins with you. You have ten bags with you and you can put any number of coins in each of the bags. The condition is that if someone asks you for any amount between 1 and 1000, you must be able to give that amount by just giving the bag (you are not allowed to open the bag and give coins).

How will you do it?

At my favorite fruit stand,
an orange costs 18,
a pineapple costs 27,
and a grape costs 15.
Using the same logic, can you tell how much a mango costs?

You walk into a room that contains a match, a kerosene lamp, a candle and a fireplace. What would you light first?

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

There was a strange boy who was born before his father. How can this be possible?

Who is generally closer to the kids, mom or dad?

(it's a funny riddle)

A convention is held where all the big logicians are summoned. The master places a band on everyone's forehead. Now all of them can see others bands but can't see his own. Then they are told that there are different colours of bands. All the logicians sit in circle and they are further explained that a bell will ring at regular intervals. The moment when a logician knew the colour of band on his forehead, he will leave at the next bell. If anyone leaves at the wrong bell, he will be disqualified.

The master assures the logicians that the puzzle will not be impossible for anyone of them. How will the logicians manage ?

Which number should replace the question mark?