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用简便方法计算.①9.98×78+22×9.98②4.9+5.56+4.34+515.

题目详情
用简便方法计算.
①9.98×78+22×9.98             
②4.9+5.56+4.34+5
1
5


1
5
1
5
1155
▼优质解答
答案和解析
①9.98×78+22×9.98,
=9.98×(78+22),
=9.98×100,
=998;

②4.9+5.56+4.34+5
1
5

=(4.9+5.2)+(5.56+4.34),
=10.1+9.9,
=20.
1
5
111555,
=(4.9+5.2)+(5.56+4.34),
=10.1+9.9,
=20.