How can one talk without saying a single word?

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.

The square root of number 121 is "11". What is the square root of the number "12345678987654321."?

How can you leave a room with two legs and return with six legs?

No matter how little or how much you use me, you change me every month. What am I?

John can eat 27 chocolates in an hour, Jacob can eat 2 chocolates in 10 minutes, and Jolly can eat 7 chocolates in 20 minutes. How long will it take them to share and eat a box of 120 chocolates whilst playing Chess?

Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

I went to the bookshop and spent one-half of the money that was in my purse.

When I came out, I found that I had as many cents as I had dollars and half as many dollars as I had cents when I went in. Find the money in my purse when I entered the store.

10+10 and 11+11 can give you the same answer.

Explain how?

I look at you, you look at me, I raise my right, you raise your left. What am I?