1.9+19.9+199.9+1999.9

分类: 作业答案 • 2021-12-19 16:49:58

问题描述：

答

1.9+19.9+199.9+1999.9
(1.9+0.1)+(19.9+0.1)+(199.9+0.1)+(1999.9+0.1)-0.4
= 2+20+200+2000-0.4
= 2222-0.4
= 2221.6