Question

The door code to gain access to a top-secret laboratory is 6 digits. The first 3 digits of the code are all odd, and the last 3 digits are all even. Digits can be used more than once. How many possible codes are there?

Answer 1

5 odd numbers and 5 even numbers
since they can be repeated
5*5*5=first 3 digits
5*5*5=last 3 digits
in all
5*5*5*5*5*5=15625 ways