Question

初一数学，急急急！！！！！

计算：1. 211×（-455）+365×455-211×545+545×365= ____
2. 37.9×0.0038+1.21×0.379+6.21×0.159=____

简便运算，写明过程，谢！！！

Answer 1

1.
原式=-221*455+365*455-221*545+545*365
=-221*455-221*545+365*455+545*365
=-221*（455+545）+365*（455+545）
=-221*1000+365*1000
=（-221+365）*1000
=144*1000
144000
2. 原式=0.379*0.38+1.21*0.379+6.21*0.159
=0.379*（0.38+1.21）+6.21*0.159
=0.379*1.59+0.621*1.59
=1.59*（0.379+0.621）
=1.59*1
=1.59