奇思妙算(用简便方法计算下面各题)(1)78×56×87-13(2)79÷215+29×511 (3)( 29×13-29 )÷13
奇思妙算(用简便方法计算下面各题)(1)78×56×87-13(2)79÷215+29×511(3)(29×13-29)÷13....
奇思妙算(用简便方法计算下面各题)(1)78×56×87-13(2)79÷215+29×511 (3)( 29×13-29 )÷13.
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(1)
×
×
-
=(
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=1×
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=
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(2)
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=1×
=
(3))(
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=(13-1)×
×3
=12×
7 |
8 |
5 |
6 |
8 |
7 |
1 |
3 |
=(
7 |
8 |
8 |
7 |
5 |
6 |
1 |
3 |
=1×
5 |
6 |
1 |
3 |
=
5 |
6 |
1 |
3 |
=
1 |
2 |
(2)
7 |
9 |
1 |
5 |
2 |
9 |
5 |
11 |
=
7 |
9 |
5 |
11 |
2 |
9 |
5 |
11 |
=(
7 |
9 |
2 |
9 |
5 |
11 |
=1×
5 |
11 |
=
5 |
11 |
(3))(
2 |
9 |
2 |
9 |
1 |
3 |
=(13-1)×
2 |
9 |
=12×