题目内容
能用简便算法的就用简便算法 19.8+86.43+20.2 | 85×101-85 |
15.52-1.6×5-5.7 | [10.5-(5.6+3.2)]÷6.8. |
解:(1)19.8+86.43+20.2,
=19.8+20.2+86.43,
=40+86.43,
=126.43;
(2)85×101-85,
=85×(101-1),
=85×100,
=8500;
(3)15.52-1.6×5-5.7,
=15.52-8-5.7,
=7.52-5.7,
=1.82;
(4)[10.5-(5.6+3.2)]÷6.8,
=[10.5-8.8]÷6.8,
=1.7÷6.8,
=0.25.
分析:(1)运用加法交换律简算;
(2)运用乘法分配律简算;
(3)先算乘法,再从左到右计算减法;
(4)先算小括号里面的加法,再算中括号里面的减法,最后算括号外的除法.
点评:此题主要考查小数的四则混合运算的运算顺序,以及应用运算定律进行简便计算的能力.
=19.8+20.2+86.43,
=40+86.43,
=126.43;
(2)85×101-85,
=85×(101-1),
=85×100,
=8500;
(3)15.52-1.6×5-5.7,
=15.52-8-5.7,
=7.52-5.7,
=1.82;
(4)[10.5-(5.6+3.2)]÷6.8,
=[10.5-8.8]÷6.8,
=1.7÷6.8,
=0.25.
分析:(1)运用加法交换律简算;
(2)运用乘法分配律简算;
(3)先算乘法,再从左到右计算减法;
(4)先算小括号里面的加法,再算中括号里面的减法,最后算括号外的除法.
点评:此题主要考查小数的四则混合运算的运算顺序,以及应用运算定律进行简便计算的能力.
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