Question

3.9×9.9+0.38的简便运算？

Answer 1

3.9×9.9+0.38
＝3.9x9.9＋3.8x0.1
＝3.9x9.9＋3.9x0.1一0.1x0.1
＝3.9×（9.9十0.1）一0.01
＝3.9x10一0.01
＝39一0.01
＝38.99

Answer 2

＝3.9×(10-0.1)+0.38
＝3.9×10-3.9×1+0.38
＝39+3.9+3.8
＝46.7
乘法分配率

Answer 3

此题简便运算的核心就是把其中的一个小数9.9转化成10－0.1，然后用乘法分配率进行计算，口算即可得出结果为39－0.01=38.99

Answer 4

3.9×9.9+0.38
=3.9×（10一0.1）+0.38
=3.9×10一3.9×0.1+0.38
=39一（0.39一0.38）
=39一0.01
=38.99

Answer 5

3.9×9.9+0.38
=3.9ⅹ(10－0.1)+0.38
=39－0.39+0.38
=39－0.01
=38.99