Find a 9-digit number, which you will gradually round off starting with units, then tenth, hundred etc., until you get to the last numeral, which you do not round off. The rounding alternates (up, down, up ...). After rounding off 8 times, the final number is 500000000. The original number is commensurable by 6 and 7, all the numbers from 1 to 9 are used, and after rounding four times the sum of the not rounded numerals equals 24.

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

What occurs twice in a week, once in a year but never in a day?

Can you find the six hidden animals in the picture below?

Solve this riddle by finding the odd one out from the rest.

Can you write down eight eights so that they add up to one thousand?

What will you call your mother's brother's brother-in-law?

You are given a cube that is made with the help of 10x10x10 smaller cubes summing up to a total of 1000 smaller cubes. You are asked to take off one layer of the cubes.
How many remain now?

In the picture given below, can you find out which digit will take place of the question mark?

What numbers should go on the bottom line?
3 6 9 15
8 2 10 12
11 8 19 27
19 10 29 39
? ? ? ?