What is the word or phrase?

If you remove one from eleven, it becomes ten. If you remove one from nine, it becomes ten.

How is this possible?

The person who makes it has no need for it. He who purchases it does not use it. The person who does use it does not know they are. What is it?

A man always keeps a spare tyre in his car. To make full use of all the five tyres, he changes the tyres in a manner that for a distance of 1, 00,000 km, each of them runs the same distance.

Can you calculate the distance travelled by each tyre on that journey?

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

John was running from 40 thieves. John has got 3 gold boxes which weigh as 4kg, 2kg, and 1kg respectively. A witty man asked John to stay with him for seven days in exchange for 1kg gold per day. John needs to stay there for seven days and also do not want to give the witty man any advance. How can John pay for his seven days stay?

Why do people go to bed?

What is in seasons, seconds, centuries and minutes but not in decades, years or days?

A man in a car saw a Golden Door, Silver Door and a Bronze Door. What door did he open first?

Two old friends, Jack and Jill, meet after a long time, and discussing as:

Jack: Hey, how are you, man?

Bill: Not bad, got married and I have three kids now.

Jack: That's awesome. How old are they?

Bill: The product of their ages is 72 and the sum of their ages is the same as your birth date.

Jack: Cool..But I still don't know.

Bill: My eldest kid just started taking piano lessons.

Jack: Oh, now I get it.

How old are Bill's kids?