00:01
A bank assigns random four -digit numbers for atm access codes.
00:07
In each code, no digit is repeated.
00:09
Use combinations to find the number of ways four digits can be chosen from 10 digits.
00:15
I didn't say here that order mattered.
00:19
But it did say use combinations.
00:21
So how many different ways can we use this would be a combination? but i know from digging with this that order would matter because it would be a different number.
00:31
If we chose things in a different order.
00:34
So i'm going to just think of that, that the order does matter.
00:37
So when i do that, i choose the numbers.
00:40
There's 10 digits.
00:41
It means that we can choose 10 ways to get the first number.
00:44
Since we can't repeat the numbers, we know that there's only nine digits left.
00:48
So there'd be nine ways to get the next number.
00:53
Then we have eight, and then we would have seven.
00:57
So when we multiply this together, that's going to give us the total.
01:01
Number of ways we can get an atm code...