1X36=36,2X18=36,3X12=36,4X9=36,6X6=36,36的因数有1,2,3,4,6,9,12,18,36
1X54=54,2X27=54,3X18=54,6X9=54,54的因数有1,2,3,6,9,18,27,54
36和54的公因数有1,2,3,6,9,18,因此36和54的最大公因数是18