Find the Next Number in the Sequence

2 9 3 1 8 4 3 6 5 7 ?

John walks into the daily grocery shop and steals a $100 bill from the shop. An hour later John returns to the shop and buys some daily products for $40. John pays the owner the $100 bill and therefore the owner returns him $60.

How much money did the owner lose?

There is a square piece of paper with a hole that is denoted by the circle on the top right side in the given picture. You have to cut the paper in a manner that it forms two and only two separate pieces of paper and then rearrange the pieces in a manner that the holes come in the centre of the paper.

John: "Hi Teacher, What is your favourite movie ?".
Chemistry Teacher: "Indium Cerium Platinum Iodine Oxygen Nitrogen".
Ten seconds later... John replied I got it.

Do you?

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

Can you write down eight eights so that they add up to one thousand?

What has many keys but can’t open a single lock?

An exterior architect is asked by a builder to plant seven trees in a manner that there are exactly six rows of trees in a straight line and each row has three trees in particular.

How will he do it?

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 ?

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