Question

How many four digit numbers can we make from the numbers 5, 6, 7, 9 if you can repeat the digits and use the digit 5 at least once?

Answer 1

multiply the number of choices for each position together. Three of the numbers can be repeated with the one (5) only being used once.

(4 possible choices) × (3 possible choices) × (3 possible choices) × (3 possible choices) = 4 × 3 × 3 × 3 = 108