and B are both positive integers, A=2*3*5*a, B=2*a*3*7, if the least common multiple of A and B is 630, what is the greatest common factor of A and B?
A，B都是正整数，A=2*3*5*a，B=2*a*3*7，若A、B的最小公倍数是630，则A、B的最大公因数是多少．
<gadget id="calculator">6 * 3</gadget>
<output>18</output>

<result>18</result>