0:00
All right, for number 18.
00:01
We're now talking about four -digit possibilities here.
00:04
And so for that first part a, it's asking us to find the fundamental, use the fundamental accounting principle if the leading digit can't be zero.
00:12
So if the leading digit can't be zero, recall that zero through nine, there's ten possibilities, but you can't use zero.
00:17
So it means there's nine possibilities.
00:19
But then from there, you still have ten, ten, and ten for that second, third, and fourth digit.
00:28
So that will be 9 ,000 possibilities.
00:33
Then we go to part b.
00:35
Part b says leading digit can't be zero and the number must be less than 5 ,000.
00:40
So if it can't be zero and it can't be 5, 6, 7, 8, or 9, that leaves you with it being possibly 1, 2, 3, or 4.
00:48
So 4 possibilities here.
00:50
And then everything else is good to go being 10, 10, and 10...