早教吧 育儿知识 作业答案 考试题库 百科 知识分享

用简便方法计算.(1)5.85+1.89+2.15(2)24.8+14.6+15.4(3)42.5-22.17-7.83(4)3.8+1.37+6.2+12.63.

题目详情
用简便方法计算.
(1)5.85+1.89+2.15    
(2)24.8+14.6+15.4
(3)42.5-22.17-7.83   
(4)3.8+1.37+6.2+12.63.
▼优质解答
答案和解析
(1)5.85+1.89+2.15    
=5.85+2.15+1.89
=8+1.89
=9.89;

(2)24.8+14.6+15.4
=24.8+(14.6+15.4)
=24.8+30
=54.8;

(3)42.5-22.17-7.83   
=42.5-(22.17+7.83)
=42.5-30
=12.5;

(4)3.8+1.37+6.2+12.63 
=(3.8+6.2)+(1.37+12.63)
=10+14
=24.