How many different telephone numbers are possible if they must have atleast one '3' and two '7's?

it is a 7 digit phone number.

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- September 28th 2011, 04:21 PMsamiivPermutations Problems
How many different telephone numbers are possible if they must have atleast one '3' and two '7's?

it is a 7 digit phone number. - September 28th 2011, 04:23 PMpickslidesRe: Permutations Problems
What is the length of the phone number in question?

- September 28th 2011, 04:34 PMsamiivRe: Permutations Problems
there are 7 digits in the phone number

- September 28th 2011, 05:05 PMpickslidesRe: Permutations Problems
Well here are the combinations

X represents the variable which is 1,2,4,5,6,8,9,0.

773XXXX

7733XXX

77333XX

773333X

7733333 - September 28th 2011, 05:24 PMsamiivRe: Permutations Problems
so the permutations would be 7!/2!