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.
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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