A rubber ball keeps on bouncing back to 2/3 of the height from which it is dropped. Can you calculate the fraction of its original height that the ball will bounce after it is dropped and it has bounced four times without any hindrance ?

How can you write nineteen in a manner that if we take out one, it becomes twenty?

We have arranged an array of numbers below. What you have to do is use any kind of mathematical symbol you know excluding any symbol that contains a number like cube root. You can use any amount of symbols but you have to come up with a valid equation for all of them.

0 0 0 = 6
1 1 1 = 6
2 + 2 + 2 = 6
3 3 3 = 6
4 4 4 = 6
5 5 5 = 6
6 6 6 = 6
7 7 7 = 6
8 8 8 = 6
9 9 9 = 6

What has 88 keys?

A Scientist was fifty years old in the year 2000 but he was forty years old in the year 2010. How can this be possible?

PS: It has a logical answer.

When I go in I might cause pain. I cause you to spit and ask you not to swallow. I can fill your hole. What am I?

A finger goes in me. You fiddle with me when you're bored. The best man always has me first. What am I?

Can you find the company name in the pictogram below?

Buy me, smell me or deliver me, I do not change.

Who am I?

If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?