能简算的要简算 ①2004×②1.25÷(5+0.25)③4.9÷+3.7÷-1.6×1④×2+3×0.75⑤(1-×)÷(+)⑥(+)×.
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解:
①2004×,
=(2003+1)×,
=2003×+1×,
=25+,
=25,
②1.25÷(5+0.25),
=1.25÷5.25,
=;
③4.9÷+3.7÷-1.6×1,
=4.9×+3.7×-1.6×,
=(4.9+3.7-1.6)×,
=7×,
=10;
④×2+3×0.75,
=0.75×2+3×0.75,
=(2+3)×0.75,
=6×0.75,
=4.5;
⑤(1-×)÷(+),
=(1-0.3)÷,
=0.7÷,
=1.12;
⑥(+)×,
=×+×,
=+,
=.
解析分析:①根据乘法分配律进行计算;②先算加法,再算除法;③根据乘法分配律进行计算;④根据乘法分配律进行计算;⑤先算小括号里面的乘法和加法,再算小括号里面的减法,最后算除法;⑥根据乘法分配律进行计算.
点评:四则运算,先弄清运算顺序,然后再进行计算,能简算的要简算.