问题
解答题
用简便方法计算. ①5%×9.9; ②4.62+9.9; ③4
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答案
①5%×9.9;,
=5%×(10-0.1),
=5%×10-5%×0.1,
=0.5-0.005,
=0.495;
②4.62+9.9,
=(4+0.62)+(10-0.1),
=(4+10)+(0.62-0.1),
=14+0.52,
=14.52;
③4
×0.6+0.6÷2 3
,3 14
=
×0.6+0.6×14 3
,14 3
=
×(0.6+0.6),14 3
=
×1.2,14 3
=
×14 3
,6 5
=
.28 5