Question

4.5×4.9+0.45×300+0.0452.1怎么简便运算

Answer 1

观察得4.5，0.45和0.045的关系，即4.5=0.45*10=0.045*100 ，原式等于0.045*100*4.9+0.045*10*300+0.045*2.1=0.045*（490+3000+2.1）=157.1445

Answer 2

4.5×4.9+0.45×300+0.045×2.1
=4.5×4.9+4.5×30+4.5×0.021
=4.5×5-4.5×0.1+135+4.5×0.02+4.5×0.001
=22.5-0.45+135+0.09+0.0045
=157.05+0.0945
=157.1445