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

Krish is 45 years old and his mother Crishtina is 73 years old.

Can you find out how many years ago, his mother was three times his age?

Can you make numbers like 24, using numbers 3,3,7 & 7 with any arithmetic operator?

It belongs to you, but other people use it more than you do. What is it?

In a science lab, a petri dish hosts a healthy colony of yeast for an experiment. Now every minute, all the yeast cells divide into two. At noon, there was just a single cell of yeast and at 1:22, the Petri dish was half full. Can you calculate when the dish will be full of yeast?

I am the beginning of everything, the end of everywhere. I'm the beginning of eternity, the end of time and space. What am I?

What is common among 11, 69, and 88?

Can you arrange four 9's and use at most 2 math symbols, to make the total 100?

My first is in chocolate but not in ham. My second is in cake and also in jam. My third at tea time is easily found. Altogether, this is a friend who is often around. What is it?

I can sizzle like bacon,
I am made with an egg,
I have plenty of backbone, but lack a good leg,
I peel layers like onions, but still remain whole,
I can be long, like a flagpole, yet fit in a hole.