题目内容
简算.
①
+
+
+
+…+
②
③57.5-14.25-15
④
×102.31+10
×102.31.
①
| 1 |
| 1×2 |
| 1 |
| 2×3 |
| 1 |
| 3×4 |
| 1 |
| 4×5 |
| 1 |
| 199×200 |
②
| 382+498×381 |
| 382×498-116 |
③57.5-14.25-15
| 3 |
| 4 |
④
| 1 |
| 7 |
| 6 |
| 7 |
①
+
+
+
+…+
,
=1-
+
-
+
-
+
-
+…
-
,
=1-
,
=
;
②
,
=
,
=
,
=
,
=1;
③57.5-14.25-15
,
=57.5-14.25-15.75,
=57.5-(14.25+15.75),
=57.5-30,
=27.5;
④
×102.31+10
×102.31,
=(
+10
)×102.31,
=(10+1)×102.31,
=10×102.31+102.31,
=1023.1+102.31,
=1125.41.
| 1 |
| 1×2 |
| 1 |
| 2×3 |
| 1 |
| 3×4 |
| 1 |
| 4×5 |
| 1 |
| 199×200 |
=1-
| 1 |
| 2 |
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 3 |
| 1 |
| 4 |
| 1 |
| 4 |
| 1 |
| 5 |
| 1 |
| 199 |
| 1 |
| 200 |
=1-
| 1 |
| 200 |
=
| 199 |
| 200 |
②
| 382+498×381 |
| 382×498-116 |
=
| 382+498×381 |
| (381+1)×498-116 |
=
| 382+498×381 |
| 381×498+498-116 |
=
| 382+498×381 |
| 382+498×381 |
=1;
③57.5-14.25-15
| 3 |
| 4 |
=57.5-14.25-15.75,
=57.5-(14.25+15.75),
=57.5-30,
=27.5;
④
| 1 |
| 7 |
| 6 |
| 7 |
=(
| 1 |
| 7 |
| 6 |
| 7 |
=(10+1)×102.31,
=10×102.31+102.31,
=1023.1+102.31,
=1125.41.
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