00:02
In this problem, it is said that a realtor uses a lockbox to store the keys to a house that is for sale, and the access code for this box consists of four digits.
00:11
The first digit cannot be three, the last digit needs to be odd, then how many different codes are available? so each code will have four digits, so one, two, three, and four.
00:24
Now, note that it is said that the first digit cannot be three.
00:28
So this first digit will be any one of the 10 digits from 0 to 9 except for 3.
00:33
So that means there are nine options to choose from when we consider this first digit.
00:38
Also, it is said that the last digit, that's this digit over here, this must be odd.
00:43
So it will be either 1 or 3 or 5 or 7 or 9...