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脱式计算.能简算的要简算9.81×0.1+0.5×98.1+0.049×981 2÷[(2-1.2)×+0.05]100-32×0.125×0.25[1-(-)]×.

编辑:chaxungu时间:2026-04-27 10:38:28分类:小学数学题库

脱式计算,能简算的要简算
9.81×0.1+0.5×98.1+0.049×981  
2数学公式÷[(2数学公式-1.2)×数学公式+0.05]
100-32×0.125×0.25
[1-(数学公式-数学公式)]×数学公式.解:(1)9.81×0.1+0.5×98.1+0.049×981,
=98.1×0.01+0.5×98.1+0.49×98.1,
=98.1×(0.01+0.5+0.49),
=98.1×(0.51+0.49),
=98.1×1,
=98.1;

(2)2÷[(2-1.2)×+0.05],
=2÷[×+0.05],
=2÷[+],
=
=


(3)100-32×0.125×0.25,
=100-4×8×0.125×0.25,
-100-(4×0.25)×(8×0.125),
=100-1×1,
=100-1,
=99;

(4)[1-(-)]×
=[1-
=×
=
分析:(1)先根据积不变规律,把9.81×0.1变成98.1×0.01,0.049×981变成0.49×98.1,再根据乘法分配律简算;
(2)先算小括号里面的减法,再算中括号里面的乘法,然后算中括号里面的加法,最后算括号外的除法;
(3)先把32分解成4×8,再运用乘法结合律简算,最后算减法;
(4)先算小括号里面的减法,再算中括号里面的减法,最后算括号外的乘法.
点评:本题考查了运算定律与简便运算,四则混合运算.注意运算顺序和运算法则,灵活运用所学的运算律简便计算.