题目内容
用简便方法计算,并要写出主要的简算过程.
①
+
+
+
②12.5×8×4×0.25
③5-
÷
-
④4.9×6.4+14×0.36-6.4×3.5.
①
| 7 |
| 11 |
| 1 |
| 5 |
| 4 |
| 11 |
| 3 |
| 5 |
②12.5×8×4×0.25
③5-
| 9 |
| 4 |
| 45 |
| 8 |
| 3 |
| 5 |
④4.9×6.4+14×0.36-6.4×3.5.
①
+
+
+
,
=(
+
)+(
+
),
=1+
,
=1
;
②12.5×8×4×0.25,
=(12.5×8)×(4×0.25),
=100×1,
=100;
③5-
÷
-
,
=5-
×
-
,
=5-
-
,
=5-(
+
),
=5-1,
=4;
④4.9×6.4+14×0.36-6.4×3.5,
=(4.9-3.5)×6.4+14×0.36,
=1.4×6.4+1.4×3.6,
=1.4×(6.4+3.6),
=1.4×10,
=14.
| 7 |
| 11 |
| 1 |
| 5 |
| 4 |
| 11 |
| 3 |
| 5 |
=(
| 7 |
| 11 |
| 4 |
| 11 |
| 1 |
| 5 |
| 3 |
| 5 |
=1+
| 4 |
| 5 |
=1
| 4 |
| 5 |
②12.5×8×4×0.25,
=(12.5×8)×(4×0.25),
=100×1,
=100;
③5-
| 9 |
| 4 |
| 45 |
| 8 |
| 3 |
| 5 |
=5-
| 9 |
| 4 |
| 8 |
| 45 |
| 3 |
| 5 |
=5-
| 2 |
| 5 |
| 3 |
| 5 |
=5-(
| 2 |
| 5 |
| 3 |
| 5 |
=5-1,
=4;
④4.9×6.4+14×0.36-6.4×3.5,
=(4.9-3.5)×6.4+14×0.36,
=1.4×6.4+1.4×3.6,
=1.4×(6.4+3.6),
=1.4×10,
=14.
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