Question

小学简便运算，要写步骤!

47.8+4.78*8.9=
20.64*1.8-17.2=

Answer 1

47.8+4.78*8.9=4.78*10+4.78*8.9
=4.78*（10+8.9）
=4.78*18.9
=4.78*（20-1.1）
=4.78*20-4.78*1.1
=95.6-5.258
=90.342

20.64*1.8-17.2
=20.64*（2-0.2）-17.2
=20.64*2-20.64*0.2-（20-2.8）
=41.28-4.128-20+2.8
=19.952

Answer 2

=4.78*10+4.78*8.9
=4.78*18.9
=90.342

Answer 3

1 先计算乘法得42.542 ，后用加法得90.342
2 先计算乘法得37.152 ，后用减法得19.952