脱式计算.(能简算的要简算)
(1.6×+3.6÷)×??????????????
3.14×+2.625×3.14
[-(0.5+×50%)]÷?????????
1.8×25%+0.25×2.2.
网友回答
解:(1)(1.6×+3.6÷)×,
=(1+3.6×)×,
=(1+4.8)×,
=5.8×,
=0.8;
(2)3.14×+2.625×3.14,
=3.14×0.375+2.625×3.14,
=(0.375+2.625)×3.14,
=3×3.14,
=9.42;
(3)[-(0.5+×50%)]÷,
=[-(+×)]÷,
=[-(+)]÷,
=[-]÷,
=×,
=;
(4)1.8×25%+0.25×2.2,
=1.8×0.25+0.25×2.2,
=(1.8+2.2)×0.25,
=4×0.25,
=1.
解析分析:(1)先算括号内的乘法和除法,再算括号内的加法,最后算括号外的乘法;(2)把分数化为小数,运用乘法分配律的逆运算简算;(3)把0.5和50%化为分数,然后按运算顺序计算,先算小括号内的乘法,再算小括号内的加法,然后算中括号内的减法,最后算中括号外的除法;(4)把25%化为小数,运用乘法分配律的逆运算简算.
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定律简便计算.