Question

4.2×17.8-42×0.78简便计算过程？

Answer 1

4.2×17.8-42×0.78
＝4.2×17.8-4.2×7.8
＝4.5×(17.8-7.8)
＝4.5×10
＝45
两个数相乘，一个数增大十倍，另外一个数缩小十倍，乘积不变

Answer 2

=(4.2*17.8-42*0.78)/1
=(76.36-32.76)/1
=43.6/1
=43.6

Answer 3

=4.2*17.8-4.2*7.8=4.2*（17.8-7.8）=4.2*10=42