Question

How many different license plate number can be made using 2 letters followed by 4 digits selected from the digits 0-9

a) if letters and digits may be repeated?
b) if letters may be repeated, but digits may not be repeated?
c) if neither letters nor digits may re repeated?

Answers

Kelley
it was suppose to say pre cal sorry
bobpursley
letters: usually do not use O.
Let N be number of letters, ten the number of numerals.

a) N*N*10^4
b) N*N*10!/(10-4)!
c) N!/(N-2)! * 10!/(10-4)!

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