用简便方法计算. ①3.5%×9.9 ②4.62+9.9 ③7.25×1.8+27.5×0.18.
题目
用简便方法计算.
①3.5%×9.9
②4.62+9.9
③7.25×1.8+27.5×0.18.
答案
①3.5%×9.9
=0.035×(10-0.1)
=0.035×10-0.035×1
=0.35-0.035
=0.315
②4.62+9.9
=4.62+10-0.1
=14.62-0.1
=14.52
③7.25×1.8+27.5×0.18
=7.25×1.8+2.75×1.8
=(7.25+2.75)×1.8
=10×1.8
=18
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