median
don steward
mathematics teaching 10 ~ 16

Tuesday, 1 June 2010

tables practice

given a pair of numbers, (a, b) find the smallest number, c so that
when you add this to one of the pair the other will divide (exactly) into this total

b is a factor of a + c
and
a divides into b + c

(3, 8) is 13 because
13 + 3 divides by 8 and
13 + 8 divides by 3

(5, 7) is 23
5 + 23 divides by 7 and
7 + 23 divides by 5

(6, 8) is 10
6 + 10 divides by 8
8 + 10 divides by 6

what if the pair are co-prime?

otherwise you need to divide by the hcf first and then what?

(10, 15) is 5
(12, 18) is 6

(1, anything) needs special consideration...

why do these rules work?

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