Question

A pass code contains 6 digits. The first 3 digits of the code are all even (2,4,6, or 8) and the last 3 are all odd (1,3,5,7, or 9). If digits can be used more than once, how many possible codes are there?

Answer 1

8000

Explanation:

The first 3 digits each have 4 options.

The last 3 digits each have 5 options.

The number of possible codes is:

4 × 4 × 4 × 5 × 5 × 5

= 4³ × 5³

= 8000