8.9十12.9用简便计算怎么列式法？

Question

如题所述

Answer 1

8.9+12.9简便计算方法是：（9-0.1）+（13-0.1）=9+13-（0.1+0.1）=22-0.2=21.8

Answer 2

8.9十12.9用简便计算可以这么列式的：
8.9+12.9
=8+0.9+13-0.1
=(8+13)+(0.9-0.1)
=21+0.8
=21.8。

Answer 3

简便计算
8.9+12.9
=9-0.1+13-0.1
=（9+13）-（0.1+0.1）
=22-0.2
=21.8

Answer 4

8.9+12.9
=9+13-0.1-0.1
=22-0.2
=21.8

Answer 5

8.9+12.9
=8.9+（11.8+1.1）
=8.9+1.1+11.8
=10+11.8
=21.8