题目内容
下面各题怎样简便就怎样算.
5÷(7÷11)÷(11÷16)÷(16÷35)
28.67×67+3×286.7+573.4×
10×(4+2)-1÷12.5%
.
解:(1)5÷(7÷11)÷(11÷16)÷(16÷35),
=5÷÷÷,
=5×××,
=25;
(2)28.67×67+3×286.7+573.4×;
=28.67×67+3.2×286.7+573.4×0.05,
=28.67×67+32×28.67+28.67,
=(67+32+1)×28.67,
=100×28.67,
=2867;
(3)10×(4+2)-1÷12.5%,
=10×(4.4+2.5)-1÷,
=10×6.9-1×,
=69-8,
=61;
(4),
=,
=.
分析:(1)把括号内的除法写成分数的形式,原式变为5÷÷÷,然后把除法改为乘法,约分即可;
(2)把分数化为小数,并根据积不变的规律,原式变为28.67×67+32×28.67+28.67,运用乘法分配律简算;
(3)根据题目特点,把分数化为小数,把百分数化为分数,计算较为简便;
(4)根据数字特点,分子部分拿出1991,分母拿出2002,分子与分母剩余部分相同,约分即可得出.
点评:在做这类问题时,首先注意审题,根据题目特点,运用运算定律或运算技巧,化繁为简,化难为易,进行巧妙解答.
=5÷÷÷,
=5×××,
=25;
(2)28.67×67+3×286.7+573.4×;
=28.67×67+3.2×286.7+573.4×0.05,
=28.67×67+32×28.67+28.67,
=(67+32+1)×28.67,
=100×28.67,
=2867;
(3)10×(4+2)-1÷12.5%,
=10×(4.4+2.5)-1÷,
=10×6.9-1×,
=69-8,
=61;
(4),
=,
=.
分析:(1)把括号内的除法写成分数的形式,原式变为5÷÷÷,然后把除法改为乘法,约分即可;
(2)把分数化为小数,并根据积不变的规律,原式变为28.67×67+32×28.67+28.67,运用乘法分配律简算;
(3)根据题目特点,把分数化为小数,把百分数化为分数,计算较为简便;
(4)根据数字特点,分子部分拿出1991,分母拿出2002,分子与分母剩余部分相同,约分即可得出.
点评:在做这类问题时,首先注意审题,根据题目特点,运用运算定律或运算技巧,化繁为简,化难为易,进行巧妙解答.
练习册系列答案
相关题目