题目内容
| 巧算下面各题. (1)5283+1396-283 |
(2)4325-1347-325 | (3)4328-(328+497) | (4)8495-(495-287) |
| (5)1825+(175+348) | (6)576+(432-176 ) | (7)1242-396 | (8)1243+998. |
分析:算式+(1)、(2)可据交换进行巧算;算式(3)、(4)、(5)、(6)可据结合律进行巧算;算式(7)、(8)可用凑整法进行巧算.
解答:解:(1)5283+1396-283,
=5283-283+1396,
=5000+1396,
=6396;
(2)4325-1347-325
=4325-325-1347;
=4000-1347;
=2653;
(3)4328-(328+497),
=4328-328-497,
=4000-497,
=3503;
(4)8495-(495-287),
=8495-495+287,
=8000+287,
=8287;
(5)1825+(175+348),
=1825+175+348,
=2000+348,
=2348;
(6)576+(432-176 ),
=576-176+432,
=400+432,
=832;
(7)1242-396,
=1242-(400-4),
=1242-400+4,
=842+4,
=846;
(8)1243+998,
=1243+(1000-2),
=1243+1000-2,
=2243-2,
=2241.
=5283-283+1396,
=5000+1396,
=6396;
(2)4325-1347-325
=4325-325-1347;
=4000-1347;
=2653;
(3)4328-(328+497),
=4328-328-497,
=4000-497,
=3503;
(4)8495-(495-287),
=8495-495+287,
=8000+287,
=8287;
(5)1825+(175+348),
=1825+175+348,
=2000+348,
=2348;
(6)576+(432-176 ),
=576-176+432,
=400+432,
=832;
(7)1242-396,
=1242-(400-4),
=1242-400+4,
=842+4,
=846;
(8)1243+998,
=1243+(1000-2),
=1243+1000-2,
=2243-2,
=2241.
点评:本题主要考查了加法交换律及结合律的运用.
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