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脱式计算(能简算的要简算)①31315−21314+5215−1114②14.85-1.58×8+31.2÷1.2③2.25×35+2.75÷123+60%④1000+999-998-997+996+995-994-993+…+104+103-102-101.

题目详情
脱式计算(能简算的要简算)
3
13
15
−2
13
14
+5
2
15
−1
1
14

②14.85-1.58×8+31.2÷1.2
2.25×
3
5
+2.75÷1
2
3
+60%
④1000+999-998-997+996+995-994-993+…+104+103-102-101.
▼优质解答
答案和解析
①3
13
15
-2
13
14
+5
2
15
-1
1
14

=(3
13
15
+5
2
15
)-(2
13
14
+1
1
14
),
=9-4,
=5;

②14.85-1.58×8+31.2÷1.2,
=14.85-12.64+26,
=28.21;

③2.25×
3
5
+2.75÷1
2
3
+60%,
=2.25×0.6+2.75×0.6+0.6,
=(2.25+2.75+1)×0.6,
=6×0.6,
=3.6;

④1000+999-998-997+996+995-994-993+…+104+103-102-101,
=(1000+999-998-997)+(996+995-994-993)+…+(104+103-102-101),
=4+4+…+4,
=4×(900÷4),
=900.