Question

4.12乘10.1简便算法递等式还有8.7乘4.3加8.7乘5.7还有2.17乘2减0.42简便

Answer 1

4.12*10.1 = 4.12*(10+0.1) = 4.12*10+4.12*0.1=41.2+0.412=41.612

8.7*4.3+8.7*5.7=8.7*(4.3+5.7)=8.7*10=87

2.17*2-0.42=0.7*3.1*2-0.6*0.7=0.7*(3.1*2-0.6)=3.92