00:01
All right, so we have a variable name that must start with a letter or an underscore character.
00:08
And we want to, so it could have one, two, three, or four different characters.
00:18
Okay, so the first one has to be an underscore or a letter.
00:21
There's 26 uppercase letters and 26 lowercase letters.
00:26
And they're considered different.
00:29
And then every other digit can be, let's see.
00:33
Of, i mean, every other character can be a letter, digit, or a underscore.
00:38
So an underscore, 26 uppercase, 26 lowercase, and 10 digits.
00:50
So this is 52, 53 possibilities for the first character, and then 53 plus 10 is 63 possibilities for the second, third, and fourth character.
01:01
So if we have a one character, there's 53 ways to choose.
01:06
If we have two characters, 53 ways to choose the first and then times 63 ways to choose the second...