Calculate combinations of characters

My first post here...not really a math expert, but certainly enjoy the challenge.

I working writing a random string generator and would like to know how to calculate how many possible combinations there are for a particular combination.

I am generating a string of 2numbers followed by 2 letters (lowercase) e.g. 12ab

I think the calculation would be (breaking it down) number combinations 10*10=100 letter combinations 26*26=676

So the number of possible combinations is 100*676=67600, but this seems a lot to me so I'm thinking I am off on my calculations!!

Could someone please point me in the right direction?

Thx

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This is not a site for math experts! – Mariano Suárez-Alvarez Oct 6 '10 at 18:12
In any case, your calculation is correct. – Mariano Suárez-Alvarez Oct 6 '10 at 18:13
I thought this was going to be about characters of representations :P At any rate, +1. – BBischof Oct 6 '10 at 18:16
Excellent! Thx!! Sorry to disappoint BBischof :/ – SteveCl Oct 6 '10 at 20:50
I'm quite interested in why you think 67600 is a lot. Care to explain your intuition? – yatima2975 Oct 7 '10 at 9:57