If x & y are positive integers, is x*y a multiple of 8?

[nk2120]

(1) the Greatest Common Divisor of x and y is 10
(2) the Least Common Multiple of x and y is 100

Answer: C, both answers taken together can answer the question

can anybody explain? thanks!

[kylo]

product of two numbers (a x b) = GCD (a&b) x LCM (a&b).


Thanks!

[RonPurewal]

product of two numbers (a x b) = GCD (a&b) x LCM (a&b).


Thanks!

this is a cool fact that has also been posted elsewhere on this board.
it's somewhat obscure, but it's definitely useful; if you get the chance to apply it, it will almost certainly render the problem much, much easier.

by the way, i've never really understood the posting of "thanks" on posts such as this one. kylo, care to enlighten?
just curious.

[RonPurewal]

(1) the Greatest Common Divisor of x and y is 10
(2) the Least Common Multiple of x and y is 100

Answer: C, both answers taken together can answer the question

can anybody explain? thanks!

no.

you posted statements 1 and 2, but not the question. there is currently nothing to "explain".
what's the prompt question?

[kylo123]

@RonPurewal -
i give "thanks" to all the people who post & discuss gmat related stuffs. It also gives me an oppurtunity to improve.

[StaceyKoprince]

Thanks, kylo - that's very nice of you!