The least common multiple of two numbers A and B is 315, and the greatest common factor is 15. If the number A is 15, what is the number B?
甲、乙两数的最小公倍数是315，最大公因数是15．如果甲数是15，乙数是多少．
<gadget id="calculator">315 / 15</gadget>
<output>21</output>

<gadget id="calculator">21 * 15</gadget>
<output>315</output>

<result>315</result>