Posted by **jenny** on Wednesday, July 25, 2012 at 6:44pm.

how many 7 digit telephone numbers can be made if every other digit is even

- math -
**Reiny**, Wednesday, July 25, 2012 at 9:29pm
Not sure if the 7 digit can start with a zero, looked at my phone book and couldn't find any

could be

EOEOEOEOE , assuming the 0 with the evens

number = 4x5x5x5x5x5x5 = 4x5^6 = 62500

or could be

OEOEOEO

number = 5^7 = 78125

for a total of 140625

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