How do you go from 98 to 720 using just one letter?

People are waiting in line to board a 100-seat aeroplane. Steve is the first person in the line. He gets on the plane but suddenly can't remember what his seat number is, so he picks a seat at random. After that, each person who gets on the plane sits in their assigned seat if it's available, otherwise, they will choose an open seat at random to sit in. The flight is full and you are last in line. What is the probability that you get to sit in your assigned seat?

Two-person want to cross a river. Only one boat is present on the riverside that can carry only one person at a time.

However, they still manage to cross the river. How is it possible?

What's a single-digit number with no value?

What has hands, but can’t clap?

In the Thar desert, 3 men found a big 24L Jar is full of water. Since there is a shortage of water so they decided to distribute the water among themselves such that they all have equal amounts of it. But they only have a 13L, a 5L and an 11-litre Jar.

How do they do it?

I possess a head

I flaunt a tail

But I don't have mouth or legs

Can you find out who I am?

Why do people go to bed?

What is the centre of gravity?

If you drop me I’m sure to crack, but give me a smile and I’ll always smile back. What am I?