Question

How many different id cards can be made if there are 5 digits on a card and no digit can be repeated?

Answer 1

if no numbers can repeat then you have

1st digit = 10 numbers

2nd digit = 9 numbers

3rd digit = 8 numbers

4th digit = 7 numbers

5th digit = 6 numbers

10 * 9 * 8 * 7 *6 =30,240 different combinations