Question

脱式计算，能简算的要简算．0.8×3.9×1.25 4.87×2.34+4.8

脱式计算，能简算的要简算．0.8×3.9×1.25 4.87×2.34+4.87×7.66 0.49×9.9 60.8-7.18-12.82 2.5×3.2×12.5 3.95×7.6+2.4．

Answer 1

（1）0.8×3.9×1.25 =0.8×1.25×3.9 =1×3.9 =3.9 （2）4.87×2.34+4.87×7.66 =4.87×（2.34+7.66） =4.87×10 =48.7 （3）0.49×9.9 =0.49×（10-0.1） =0.49×10-0.49×0.1 =4.9-0.049 =4.851 （4）60.8-7.18-12.82 =60.8-（7.18+12.82） =60.8-20 =40.8 （5）2.5×3.2×12.5 =2.5×（0.4×8）×12.5 =（2.5×0.4）×（8×12.5） =1×100 =100 （6）3.95×7.6+2.4 =30.02+2.4 =32.42．