Replace the question mark with the number below given a simple math problem.

What's the only room from which no one can enter or leave

Find the last number in the series below:

voN luJ yaM raM ---

A mother bought three dress for her triplets daughters(one for each) and put the dresses in the dark. One by one the girls come and pick a dress.
What is the probability that no girl will choose her own dress?

We know that the number 7 is the prime followed by a cube. Which next number is also a prime followed by a cube?

If a wheel has 54 spokes, how many spaces are there between the spokes?

A man plots the murder of his wife. His plan is full proof. Nobody saw them leaving their house. He stabbed her with a knife while driving. She died on the spot. He threw her body in a valley. He threw the knife carefully wiping his finger prints on a random garbage bin. Then he went back to his home and no one was watching him this time as well.

After an hour, he was called by the local police department who informed him that his wife was murdered. They asked him to reach the scene of crime immediately. But as soon as he arrived at the crime scene, he was arrested by them.

How did the police know that he himself is the murderer?

There are three light switches outside a room. One of the switches is connected to a light bulb inside the room.
Each of the three switches can be either 'ON' or 'OFF'.

You are allowed to set each switch the way you want it and then enter the room(note: you can enter the room only once)

Your task is to then determine which switch controls the bulb?

Double it and multiply it by 4. Then divide it by 8 and you’ll have it once more. What number is it?

Find the next number in the series below

21 32 54 87 131 ?