题目: 下面各题怎样简便就怎样算.①4×0.8×2.5×12.5②(2.8+3.85÷3.5)×4.6. 答案: ①4×0.8×2.5×12.5,=(4×2.5)×(0.8×12.5),=10×10,=100;②(2.8+3.85÷3.5)×4.6,=(2.8+1.1)×4.6,=3.9×4.6,=17.94.