對于?$9$?和?$21$?:?$ $?先對?$9$?分解質(zhì)因數(shù):?$9 = 3×3;$?
對?$21$?分解質(zhì)因數(shù):?$21 = 3×7;$?
?$9$?和?$21$?的最小公倍數(shù)為?$3×3×7 = 63。$?
對于?$12$?和?$6$?:?$ $?因?yàn)?$12$?是?$6$?的倍數(shù),
所以?$12$?和?$6$?的最小公倍數(shù)是?$12。$?
對于?$5$?和?$14$?:?$ 5$?是質(zhì)數(shù),?$14 = 2×7,$?
?$5$?和?$14$?互質(zhì),
所以?$5$?和?$14$?的最小公倍數(shù)為?$5×14 = 70。$?