How many pluses should we put between the digits of 987654321 to get a total of 99, and where?

Replace the question mark with the correct number in below Picture:

If "P" means "-", "Q" means "/", "R" means "+", and "S" means "*" then find the value of the following:

21 Q 7 R 9 S 10 P 13

If 21x = 79x, what is the value of x?

Use the numbers 2, 3, 4 and 5 and the symbols + and = to make a true equation. Conditions: Each must be used exactly once and no other numbers or symbols can be used.

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

Can you find out the remainder when 3^300 is divided by 5?

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.

A girl is twice as old as her brother and half as old as her father. In 50 years, her brother will be half as old as his father. How old is the daughter now?

We know that the number 7 is the prime followed by a cube. Which next number is also a prime followed by a cube?