How many ways can you write abcde?

Answer 1

I guess you mean, to switch the letters around in different orders. You have 5 choices for the first letter. Whichever letter you choose, you have 4 choices for the second letter, 3 for the next, etc.; the final result is that you have 5 x 4 x 3 x 2 x 1 different options. This number (the product of all integers from 1 to 5) is written as 5! (five, followed by an exclamation), and read "5 factorial" or "factorial of five".