How many 4-letter words can we make from the letters A, B, C, and D, we are allowed to repeat letters, and we must use the letter B at least once ? (Show 2 different methods clearly
You have to think of a logical method that might work.
Hoe many ways if only one letter is used
How many ways if 2 letters are used
How many ways if 3 letters are used
How many ways if 4 letters are used.
Thinks about that and come back with some of your own input.