2.5×(0.2+0.02+20)的简便计算？拆开算就可以原式=2.5×0.2+2.5×0.02+2.5×20=0.5+0.05+50=50.55
2.5×(0.2＋0.02＋20)＝2.5×0.2＋2.5×0.02＋2.5×20＝0.5＋0.05＋50＝50.55
