number = 2*3*a, B number = 3*5*a (a is a non-zero natural number), if the greatest common factor of A and B is 21, then what is the least common multiple of A and B.
甲数=2*3*a，乙数=3*5*a(a为非0自然数)，如果甲乙两数的最大公因数是21，那么甲乙两数的最小公倍数是多少．
<gadget id="calculator">30 * 7</gadget>
<output>210</output>

<result>210</result>