Posted by Gabby ( 5 grade) on Monday, January 30, 2012 at 4:10pm.
how would you test to see whether 7 is a factor of 291?

math  Reiny, Monday, January 30, 2012 at 4:14pm
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  Gabby ( 5 grade), Monday, January 30, 2012 at 4:18pm
why 2 if the end digit is 1?

math  Reiny, Monday, January 30, 2012 at 4:21pm
notice I said, "twice" the number skipped.
2x1 = 2

math  Gabby ( 5 grade), Monday, January 30, 2012 at 4:24pm
i don't get it i want ms sue to help me!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

math  Ms. Sue, Monday, January 30, 2012 at 4:27pm
<g>
Reiny is a REAL math teacher; I'm not.
I'd just divide 291 by 7.

math  Gabby ( 5 grade), Tuesday, January 31, 2012 at 3:55pm
WOW I BELIEVED IN YOU:P
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