If 1+9+8=1, what is 2+8+9?

Take 9 from 6, 10 from 9, 50 from 40, and leave 6.

How Come ??

There are 20 people in an empty, square room. Each person has full sight of the entire room and everyone in it without turning his head or body, or moving in any way (other than the eyes). Where can you place an apple so that all but one person can see it?

What is at the end of a rainbow?

What is always in front of you but can’t be seen?

There are four 3-link chains. All you have to do is join them into a big 12-link chain. For joining two closed links, one of the links must be cut and placed onto the other link for closing.

How many minimum links will you have to cut to make the big chain?

Can you figure out the logic I used to decide the order of the following words:
gun, shoe, spree, door, hive, kicks, heaven, gate, line, den

Why do you find that most of the buildings are deprived of the 13th floor?

What seven-letter word has hundreds of letters in it?

Solve the below puzzle by replacing the question mark with the correct number.

3 6 12

4 8 16

5 10 ?