The least common multiple of the two numbers A and B is 90, the least common multiple of the two numbers B and C is 105, and the least common multiple of the two numbers A and C is 126, so what is the number A?
甲、乙两数的最小公倍数是90，乙、丙两数的最小公倍数是105，甲、丙两数的最小公倍数是126，那么甲数是多少．
<result>18</result>