Re: [MATHEDCC] Divisibility Rules

Kate Acks (Kathy.Acks@MCCADA.MAUICC.HAWAII.EDU)
Thu, 02 Oct 1997 09:01:36 -1000

There is a rule for divisibility by 7 - but is complex, and far easier
to grab a calculator and just do it!!!!

Let me see if I can remember:

Take the number 366198

Remove the last digit (8), and double it (16)

Subtract the 16 from the original number with the last digit removed:

36619-16 = 36603

Repeat the process

3660-6 = 3654

365-8 = 357

35-14 = 21

2-2 = 0

If you end with a 0, or a number divisible by 7 (such as 21, or 357) you
can stop!!

Good luck

Aloha Kate (Maui Community College)
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