解题思路:①先算除法,再算乘法,最后算加法;
②根据乘法分配律进行简算;
③根据乘法分配律进行简算;
④根据乘法分配律进行简算;
⑤先算乘法,再算减法,最后算除法;
⑥中括号里面的根据减法的性质进行简算,最后算乘法.
①375+450÷18×25
=375+25×25
=375+625
=1000;
②4.6×0.25-[3/5]÷4
=4.6×0.25-[3/5]×0.25
=(4.6-[3/5])×0.25
=4×0.25
=1;
③4.2×1.85+4.2×7.15+4.2
=4.2×(1.85+7.15+1)
=4.2×10
=42;
④[5/9]×[3/4]+[5/9]×[3/4]
=([5/9]+[5/9])×[3/4]
=[10/9]×[3/4]
=[5/6];
⑤(7.5×1.08-5.37)÷0.35
=(8.1-5.37)÷0.35
=2.73÷0.35
=7.8;
⑥[8/9]×[0.75-([7/16]-[1/4])]
=[8/9]×[0.75-[7/16]+[1/4]]
=[8/9]×[0.75+[1/4]-[7/16]]
=[8/9]×[1-[7/16]]
=[8/9]×[9/16]
=[1/2].
点评:
本题考点: 分数的四则混合运算;运算定律与简便运算;小数四则混合运算.
考点点评: 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.