29x045029x420029x13的精選

2.9×0.45+0.29×4.2+0.029×13的簡便運算步驟如下2.9×0.45+0.29×4.2+0.029×13=2.9×0.45+2.9×0.42+2.9×0.13=2.9×（0.45+0.42+0.13）=2.9×1=2.9。常用簡便運算律1、加法交換律：兩個...