题目内容
脱式计算(能简算要简算)
(1)(66-32×1.2)÷0.25 | (2)10×+17×75%-7×0.75 |
(3)0.25×(5(3-2.5×)) | (4)9.99×22.2+33.3×3.34. |
解:(1)(66-32×1.2)÷0.25,
=(66-38.4)÷0.25,
=27.6÷0.25,
=110.4,
(2)10×+17×75%-7×0.75,
=10×0.75+17×0.75-7×0.75,
=(10+17-7)×0.75,
=20×0.75,
=15,
(3)0.25×[5×(3-2.5×)],
=0.25×[5×(3-)],
=0.25×[5×],
=××,
=1,
(4)9.99×22.2+33.3×3.34,
=9.99×11.1×2+11.1×3×3.34,
=11.1×(9.99×2+3×3.34),
=11.1×(19.98+10.02),
=11.1×30,
=333.
分析:(1)(3)根据四则混合运算的运算顺序计算:先算第二级运算,再算第一级运算,有括号的要先算括号里面的.(2)(4)根据乘法分配律进行计算.
点评:本题主要考查了学生在四则混合运算中灵活运用简便算法的计算能力.
=(66-38.4)÷0.25,
=27.6÷0.25,
=110.4,
(2)10×+17×75%-7×0.75,
=10×0.75+17×0.75-7×0.75,
=(10+17-7)×0.75,
=20×0.75,
=15,
(3)0.25×[5×(3-2.5×)],
=0.25×[5×(3-)],
=0.25×[5×],
=××,
=1,
(4)9.99×22.2+33.3×3.34,
=9.99×11.1×2+11.1×3×3.34,
=11.1×(9.99×2+3×3.34),
=11.1×(19.98+10.02),
=11.1×30,
=333.
分析:(1)(3)根据四则混合运算的运算顺序计算:先算第二级运算,再算第一级运算,有括号的要先算括号里面的.(2)(4)根据乘法分配律进行计算.
点评:本题主要考查了学生在四则混合运算中灵活运用简便算法的计算能力.
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