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.

Can you count the number of triangles in the given picture?

I am white when I am dirty, and black when I am clean. What am I?

Solve below popular number sequence
314 159 265 358 979 323 846 ?

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

I am a seven-letter word but if you remove four of my letters I will have one left. What word am I?

In two decks of cards, what is the least amount of cards you must take to be *guaranteed* at least one four-of-a-kind?

A boy purchased a book from a bookkeeper and gave him $100.
The cost of the book is $50 but the bookkeeper has no change, so he gets the change from the next shop and returns the boy his $50.

After some time the next shopkeeper came with the $100 note and told the bookkeeper that the note was a fraud, so he took the money back.

How much loss did the bookkeeper face?

In the given figure, you can see that four match sticks are used to form a square. Can you form five squares by using six matches?

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