Question

How many different 4-digit numbers can be created if no digit can be

repeated? Remember, a number cannot begin with 0.

Answer 1

2

Step-by-step explanation:

1234

4567

Answer 2

Answer: 4536

Step-by-step explanation:

There are ten single digit values 0 through 9. But we cannot use 0 as the first digit, so we have 9 possible choices for the first slot.

For the second slot, we also have 9 choices because we can now pick 0.

The third slot has 8 choices.

The last slot has 7 choices.

Each time we form a new slot, the number of choices drops by 1. The exception of course is the jump from the first to second slot.

Overall, there are 9*9*8*7 = 4536 different numbers.