1) two different letters, so you first have 26 choices then (26 - 1) = 25 choices. then for the numbers you follow a similar pattern, 10 choices, then 9, then 8. multiply all these together to get

468000 possibilities

2) 26 x 25 x 9 x 9 x 8 = 421200 possibilities

to the guy above me, he said DIFFERENT letters and numbers so you cannot say 26 x 26 x 10 x 10 x 10, you have to say 26 x (26 - 1) (as you took away one choice with the initial letter) x 10 x (10 - 1) (since you took away one choice with the initial number) x (10 - 2) (as you took away another choice with the previous number). as for the second part it is 26 x 25 x 9 (10 digits - 1 because of 0) x 9 (9 digits minus the one you just used + 1 because you can now use 0) x 8

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