The last two digits of a phone number

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Question from Joshua, a student:

I want to find the last two digits of a phone number whose first eight numbers of a ten digit phone numbers are known.

Hi Joshua,

I assume you mean the rightmost digits. there are some restrictions on the left-most digits but the two right-most digits can be any digits from 00 to 99. Thus there are 100 possibilities 00, 01, 02, ... ,09, 10, 11, ... ,99.

Penny

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