题目内容
运用运算定律或性质进行简算:
(1)
-
+
-
(2)(56÷
)×
(3)7.8×101.
(1)
| 7 |
| 8 |
| 3 |
| 5 |
| 1 |
| 8 |
| 2 |
| 5 |
(2)(56÷
| 7 |
| 10 |
| 5 |
| 7 |
(3)7.8×101.
(1)
-
+
-
,
=(
+
)-(
+
),
=1-1,
=0;
(2)(56÷
)×
,
=56×
×
,
=80×
,
=57
;
(3)7.8×101,
=7.8×(100+1),
=7.8×100+7.8,
=780+7.8,
=787.8.
| 7 |
| 8 |
| 3 |
| 5 |
| 1 |
| 8 |
| 2 |
| 5 |
=(
| 7 |
| 8 |
| 1 |
| 8 |
| 3 |
| 5 |
| 2 |
| 5 |
=1-1,
=0;
(2)(56÷
| 7 |
| 10 |
| 5 |
| 7 |
=56×
| 10 |
| 7 |
| 5 |
| 7 |
=80×
| 5 |
| 7 |
=57
| 1 |
| 7 |
(3)7.8×101,
=7.8×(100+1),
=7.8×100+7.8,
=780+7.8,
=787.8.
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