(1)9.81×0.1+0.5×98.1+0.049×981
(2)15×(-)×17
(3)100-32×0.125×0.25
(4)[1-(-)]×
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解:(1)9.81×0.1+0.5×98.1+0.049×981
=9.81×0.1+5×9.81+4.9×9.81
=9.81×(0.1+5+4.9)
=9.81×10
=98.1;
(2)15×(-)×17
=15×17×-×17×15
=34-30
=4;
(3)100-32×0.125×0.25
=100-4×8×0.125×0.25
=100-(8×0.125)×(0.25×4)
=100-1×1
=100-1
=99;
(4)[1-(-)]×
=[1-]×
=×
=.
解析分析:(1)根据数字特点,原式变为9.81×0.1+5×9.81+4.9×9.81,运用乘法分配律简算;
(2)运用乘法分配律简算;
(3)把32看作4×8,运用乘法交换律与结合律简算;
(4)先算小括号内的,再算中括号内的,最后算括号外的.
点评:此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定律简便计算.