解题思路:(1)先算乘法再算除法,最后算减法;
(2)运用加法结合律简算;
(3)先把222×999变成666×333,然后再运用乘法分配律简算;
(4)先把小括号去掉(注意括号外是减法,里面的运算符合要改变),然后计算中括号里面的,最后算括号外的除法;
(5)[3/1×4]=1
−
1
4
,
[3/4×7]=[1/4]
−
1
7
,
[3/7×10]=[1/7]-[1/10]…;
有以上规律化简求解;
(6)先把(289+[5/6]+[7/8]+[7/10])÷([5/6]+[7/8]+[7/10])分成289÷([5/6]+[7/8]+[7/10])+([5/6]+[7/8]+[7/10])÷([5/6]+[7/8]+[7/10]),然后在根据商不变规律简算.
(1)2000-72×625÷36,
=2000-45000÷36,
=2000-1250,
=750;
(2)4.8-[4/17]+5.2-[13/17],
=(4.8+5.2)-([4/17]+[13/17]),
=10-1,
=9;
(3)222×999+333×334,
=666×333+333×334,
=(666+334)×333,
=1000×333,
=333000;
(4)[5[3/20]-(4.15-2[1/3])]÷3[1/3],
=[5[3/20]-4[3/20]+2[1/3]]÷3[1/3],
=[1+2[1/3]]÷3[1/3],
=3[1/3]÷3[1/3],
=1;
(5)[3/1×4]+[3/4×7]+[3/7×10]+…+[3/91×94],
=1-[1/4]+[1/4]−
1
7+[1/7]-[1/10]+…+[1/91]-[1/94],
=1-[1/94],
=[93/94];
(6)(289+[5/6]+
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;分数的巧算.
考点点评: 本题考查了较复杂的简便运算,注意找清楚规律,再根据规律化简.