计算能简算的简算
1.8×+2.2×25% (-×)÷÷-×+÷4-(-+)×12?????????÷(×)-.
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解:(1)1.8×+2.2×25%,
=1.8×0.25+2.2×0.25,
=(1.8+2.2)×0.25,
=4×0.25,
=1;
(2)(-×)÷,
=(-)×,
=×-×,
=-,
=;
(3)÷-×,
=×-×,
=(-)×,
=×,
=;
(4)+÷4-,
=+-,
=-,
=;
(5)(-+)×12,
=×12-×12+×12,
=4-2+3,
=5;
(6)÷(×)-,
=÷-,
=-,
=.
解析分析:(1)运用乘法分配律简算;
(2)先算小括号里面的乘法,再把括号外的除法变成乘法,运用乘法分配律简算;
(3)把除法变成乘法,运用乘法分配律简算;
(4)先算除法,再算加法,最后算减法;
(5)运用乘法分配律简算;
(6)先算小括号里面的乘法,再算括号外的除法,最后算减法.
点评: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.