21一0.45÷0.5一2.1简便方法?

2025-03-27 02:44:50
推荐回答(2个)
回答1:

21-0.45/0.5-2.1
=21-(0.45/0.5+2.1)
=21-(0.9+2.1)
=21-3
=18

回答2:

原式=21-0.9-2.1=21-(0.9+2.1)=21-3=18.