# maths permutation and combination

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four numbers. Find the number of possible passwords if there are no
restrictions on what three letters and what four numbers can be used.

• maths permutation and combination - answer pls check -

Pls check if my answer is correct

26C3*10C4
=26!/(26-3)!3! . 10!/(10-4)!4!
= 26*25*24*23!/23!*6 . 10*9*8*7*6!/6!*4*3*2*1
=15600/6 * 5040/24
=2600*210
=546000

• maths permutation and combination -

I didn't see that letters or numbers cant be used more than once.

26*26*26*26*10*10*10*10

As I read it AAAA0000 is allowed, your number didn't include those.

• maths permutation and combination -

Thanks

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