Question

How many 6-letter words can be made from the letters WASTEFUL if repetition of letters is allowed?

Answer 1

Well, you have 8 letters to pick from and you can repeat your choices, so
8x8x8x8x8x8
= 8^6
= 262144

Answer 2

How many 6-letter words can be made from the letters WASTEFUL if repetition of letters is not allowed?

Answer 3

48