How do you go from 98 to 720 using just one letter?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

There are two candles. Both will only burn exactly for an hour. How will you use these two candles to measure forty-five minutes?

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

I am an odd number. Take away a letter and I become even. What number am I?

Find three whole, positive numbers that have the same answer when multiplied together as when added together.

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 nine thousand, nine hundred nine dollars is written as $9,909,
how should twelve thousand, twelve hundred twelve dollars be written?

I am working in a bus company. The company recently went under expansion and therefore there was not enough room for all the buses. As a result, twelve buses had to be stored outside.

If the company decides to expand the garage space by forty percent, enough space to accommodate the current buses will be created leaving enough space for twelve more buses if the need arises in future.

Can you calculate the number of buses that the company owns at present?

Replace the 'X' with any mathematical symbol to make the expression equal to 111.

18 X 12 X 2 X 3 = 111