用简便方法计算.
①54.38+(19.5-4.38)
②25×32×7
③8×+8×+8
③756+199.
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解:①54.38+(19.5-4.38),
=54.38+19.5-4.38,
=(54.38-4.38)+19.5,
=50+19.5,
=69.5;
②25×32×7,
=25×4×8×7,
=(25×4)×(8×7),
=100×56,
=5600;
③8×+8×+8,
=(++1)×8,
=2×8,
=16;
④756+199,
=700+56+(200-1),
=700+200+(56-1),
=900+55,
=955.
解析分析:①去括号,运用加法结合律简算;②把32看作4×8,运用乘法结合律简算;③运用乘法分配律的逆运算简算;④把756看作700+56,把199看作200-1,运用加法交换律与结合律简算.
点评:完成本题要注意分析式中数据,运用合适的简便方法计算.