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用简便方法计算8.16+5.49+2.84+4.51     &nbs

来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/10/06 19:01:06
用简便方法计算
8.16+5.49+2.84+4.51           
1.29+3.7+2.71+6.3
12.98-(6.37+3.98)
36.9-10.47+3.1-10.53.
(1)8.16+5.49+2.84+4.51,
=(8.16+2.84)+(5.49+4.51),
=11+10,
=21;
(2)1.29+3.7+2.71+6.3,
=(1.29+2.71)+(3.7+6.3),
=4+10,
=14;
(3)12.98-(6.37+3.98),
=12.98-3.98-6.37,
=9-6.37,
=2.63;
(4)36.9-10.47+3.1-10.53,
=(36.9+3.1)-(10.47+10.53),
=40-21,
=19;