Find out a multi-digit number that if multiplied by the number 9 or any of its multiplications products (i.e. 18, 27, 36, 45,..) will result in the multiplication factor repeated (n) number of times.

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?

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

As easy as you can get into me, it is as hard to get out of me.

Do you know what I am?

He digs out tiny caves and stores gold and silver in them. He also built bridges of silver and made crowns of gold. They are the smallest you could imagine. Sooner or later everybody needs his help, yet many people are afraid to let him help them. Who is he?

What does this mathematical rebus means ?

If you say my name, I will no longer exist. What am I?

I have 50 feet long of cloth, I need to create 50 handkerchiefs each size of 1 foot. I take one minute to cut a 1-foot handkerchief. So how long will it take to cut 50 handkerchiefs?

Transform the word THINK into BRAIN while changing only one letter at a time in a manner that each of the word in the process is a real word!!!

What time is it when an elephant sits on a fence?