=(10+5)X(10+2)=10x10+10x2十5x10十5x2=100十20十50十10=180
15X12=15x(10+2)=15x10+15x2=150+30=180此类题目 尽量化解乘除为加减
15x12=3x5x3x4=3x3x(5x4)=3x3x20=180
15*4*3=60*3=180
f gj s ge b h g hu g感觉好玩nn
