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May 06, 2005

Comments

Mike Brown

It seems complicated, but it's basically simple. In order to put the exchange (first three digits of the phone number) to the left of the subscriber number (last four digits), you need to multiply by 10,000. Eighty times 250 is 20,000, so by dividing by two, you get the effect you wanted.

The steps of adding one and subtracting 250 is a red herring - adding one before you multiply by 250 is the same as adding 250 - you then subtract 250 and wind up back where you started. The method would work exactly the same without the addition and subtraction steps.

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