19999.9+1999.9+199.9+19.9+1.9怎么巧算

问题描述:

19999.9+1999.9+199.9+19.9+1.9怎么巧算

19999.9+1999.9+199.9+19.9+1.9
=20000+2000+200+20+2-0.5
=22221.5