解题思路:①先变形为5.4×0.9+3.6×0.9+0.9×1,再根据乘法分配律简便计算;
②把78×[3/79]变形为(79-1)×[3/79]再运用乘法的分配律进行计算即可.
③把6-
3
1
4
+[3/4]变形为3+3+[3/4]-3[3/4]再进行计算即可.
④用减法的性质先计算中括号内部的,然后再计算括号外面的.
⑤按照四则混合运算的顺序,先计算括号内部的,再计算括号外面的.
①5.4×[9/10+3.6÷
10
9+0.9
=5.4×0.9+3.6×0.9+0.9×1
=0.9×(5.4+3.6+1)
=0.9×10
=9;
②78×
3
79]
=(79-1)×[3/79]
=79×[3/79]−
3
79×1
=3-[3/79]
=2[76/79];
③6-3
1
4+[3/4]
=3+3+[3/4]-3[3/4]
=3+[(3+
3
4)-3[3/4]]
=3;
④[5/9]×[[3/4]-([7/16]-[1/4])]
=[5/9]×[([3/4+
1
4])-[7/16]]
=[5/9]×[9/16]
=[5/16];
⑤[47-(18.875-1÷[8/15])]÷0.46×[46/25]
=[47-(18.875-1.875)]×[100/46]×[46/25]
=[47-(18.875-1.875)]×4
=[47-17]×4
=30×4
=120.
点评:
本题考点: 整数、分数、小数、百分数四则混合运算;运算定律与简便运算;分数的简便计算.
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律简便计算.