math

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how would you test to see whether 7 is a factor of 291?

• math -

I would divide it out and see.

or

write down the number without the last digit
29
subtract twice the digit you skipped
29
-2
----
27

is 27 divisilbe by 7 ?
no ? , then neither was 291

for large numbers checking for divisibility by 7,
repeat the above process until you can tell.

Not very practical, but it works !!!

• math -

why 2 if the end digit is 1?

• math -

notice I said, "twice" the number skipped.
2x1 = 2

• math -

i don't get it i want ms sue to help me!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

• math -

<g>

Reiny is a REAL math teacher; I'm not.

I'd just divide 291 by 7.

• math -

WOW I BELIEVED IN YOU:P

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