12.5x0.64x2.5简便计算脱式计算=12,5×0,8×0,8×2,5=10×2=20
12.5x0.64x2.5=(12.5x0.8)x(0.4x2.5x2)=10x2=20
=12.5x0.8x0.4x2.5x2=10x1x2=20
