用简便方法计算.512
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用简便方法计算.
5 |
12 |
①
5
12×
1
13-
1
4÷13
=
5
12×
1
13-
1
4×
1
13
=(
5
12-
1
4)×
1
13
=
1
6×
1
13
=
1
78
②3.5×98+35×0.2
=35×9.8+35×0.2
=35×(9.8+0.2)
=35×10
=350
5
12×
1
13-
1
4÷13
=
5
12×
1
13-
1
4×
1
13
=(
5
12-
1
4)×
1
13
=
1
6×
1
13
=
1
78
②3.5×98+35×0.2
=35×9.8+35×0.2
=35×(9.8+0.2)
=35×10
=350