简便运算
0.04x0.25x5x40=（0.04x0.25）x（5x40）=0.01x200=2
我写给你0.04x0.25x5x40=（0.04x5）x（0.25x40）=0.2x10=2
0.04×0.25×5×40=4×0.25×5×0.4=1×5×0.4=2
0.04×0.25×5×40=(0.04×5)×(0.25×40)=0.2×10=2
