递等式计算(能简算的要简便运算):15.68-(7.78-4.32)-2.320.25×3.2×1.259.99×1.014.63×1.4+46.3×0.8617.5
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解决时间 2021-12-18 21:25
- 提问者网友:美人性情
- 2021-12-18 01:11
递等式计算(能简算的要简便运算):15.68-(7.78-4.32)-2.320.25×3.2×1.259.99×1.014.63×1.4+46.3×0.8617.5÷0.8÷12.50.9+9.9+99.9+999.9
最佳答案
- 五星知识达人网友:空山清雨
- 2021-12-18 02:26
解:①15.68-(7.78-4.32)-2.32,
=15.68-7.78+4.32-2.32,
=(15.68+4.32)-(7.78+2.32),
=20-10,
=10;
②0.25×3.2×1.25,
=0.25×4×0.8×1.25,
=(0.25×4)×(0.8×1.25),
=1×1,
=1;
③9.99×1.01,
=(10-0.01)×1.01,
=10.1-0.0101,
=10.0899;
④4.63×1.4+46.3×0.86,
=46.3×0.14+46.3×0.86,
=46.3×(0.14+0.86),
=46.3×1,
=46.3;
⑤17.5÷0.8÷12.5,
=17.5÷(0.8×12.5),
=17.5÷1,
=17.5;
⑥0.9+9.9+99.9+999.9,
=1-0.1+10-0.1+100-0.1+1000-0.1,
=(1+10+100+1000)-(0.1+0.1+0.1+0.1),
=1111-0.4,
=1110.6.解析分析:①15.68-(7.78-4.32)-2.32去掉括号,变成15.68-7.78+4.32-2.32,再利用加法的交换律和一个数连续减去两个数等于这个数减去这两个数的和计算简便;
②0.25×3.2×1.25把3.2拆成4×0.8,再利用乘法的结合律计算;
③9.99×1.01把9.99拆成10-0.01,再利用乘法的分配律计算;
④4.63×1.4+46.3×0.86把4.63×1.4变成46.3×0.14,;
⑤17.5÷0.8÷12.5变成17.5÷(0.8×12.5)计算简便;
⑥0.9+9.9+99.9+999.9变成1-0.1+10-0.1+100-0.1+1000-0.1,再利用加法的交换律和结合律计算简便.
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.
=15.68-7.78+4.32-2.32,
=(15.68+4.32)-(7.78+2.32),
=20-10,
=10;
②0.25×3.2×1.25,
=0.25×4×0.8×1.25,
=(0.25×4)×(0.8×1.25),
=1×1,
=1;
③9.99×1.01,
=(10-0.01)×1.01,
=10.1-0.0101,
=10.0899;
④4.63×1.4+46.3×0.86,
=46.3×0.14+46.3×0.86,
=46.3×(0.14+0.86),
=46.3×1,
=46.3;
⑤17.5÷0.8÷12.5,
=17.5÷(0.8×12.5),
=17.5÷1,
=17.5;
⑥0.9+9.9+99.9+999.9,
=1-0.1+10-0.1+100-0.1+1000-0.1,
=(1+10+100+1000)-(0.1+0.1+0.1+0.1),
=1111-0.4,
=1110.6.解析分析:①15.68-(7.78-4.32)-2.32去掉括号,变成15.68-7.78+4.32-2.32,再利用加法的交换律和一个数连续减去两个数等于这个数减去这两个数的和计算简便;
②0.25×3.2×1.25把3.2拆成4×0.8,再利用乘法的结合律计算;
③9.99×1.01把9.99拆成10-0.01,再利用乘法的分配律计算;
④4.63×1.4+46.3×0.86把4.63×1.4变成46.3×0.14,;
⑤17.5÷0.8÷12.5变成17.5÷(0.8×12.5)计算简便;
⑥0.9+9.9+99.9+999.9变成1-0.1+10-0.1+100-0.1+1000-0.1,再利用加法的交换律和结合律计算简便.
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.
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- 1楼网友:怀裏藏嬌
- 2021-12-18 03:26
这个答案应该是对的
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