题目内容
下面各题怎样算简便就怎样算.
(
-
)×15×25
+
+
+
+
+
+
.
(
| 4 |
| 15 |
| 1 |
| 25 |
| 1 |
| 2 |
| 3 |
| 4 |
| 7 |
| 8 |
| 15 |
| 16 |
| 31 |
| 32 |
| 63 |
| 64 |
| 127 |
| 128 |
(1)(
-
)×15×25,
=
×15×25-
×25×15,
=100-15,
=85;
(2)
+
+
+
+
+
+
,
=(1-
)+(1-
)+(1-
)+…+(1-
),
=7-(
+
+
+
+
+
+
),
=7-(1-
+
-
+
-
+
-
+
-
+
-
+
-
),
=7-(1-
),
=6+
,
=6
.
| 4 |
| 15 |
| 1 |
| 25 |
=
| 4 |
| 15 |
| 1 |
| 25 |
=100-15,
=85;
(2)
| 1 |
| 2 |
| 3 |
| 4 |
| 7 |
| 8 |
| 15 |
| 16 |
| 31 |
| 32 |
| 63 |
| 64 |
| 127 |
| 128 |
=(1-
| 1 |
| 2 |
| 1 |
| 4 |
| 1 |
| 8 |
| 1 |
| 128 |
=7-(
| 1 |
| 2 |
| 1 |
| 4 |
| 1 |
| 8 |
| 1 |
| 16 |
| 1 |
| 32 |
| 1 |
| 64 |
| 1 |
| 128 |
=7-(1-
| 1 |
| 2 |
| 1 |
| 2 |
| 1 |
| 4 |
| 1 |
| 4 |
| 1 |
| 8 |
| 1 |
| 8 |
| 1 |
| 16 |
| 1 |
| 16 |
| 1 |
| 32 |
| 1 |
| 32 |
| 1 |
| 64 |
| 1 |
| 64 |
| 1 |
| 128 |
=7-(1-
| 1 |
| 128 |
=6+
| 1 |
| 128 |
=6
| 1 |
| 128 |
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