130+142+156+172+190+1110+1132=______.
问题描述:
+1 30
+1 42
+1 56
+1 72
+1 90
+1 110
=______. 1 132
答
+1 30
+1 42
+1 56
+1 72
+1 90
+1 110
1 132
=
-1 5
+1 6
-1 6
+1 7
-1 7
+1 8
-1 8
+1 9
-1 9
+1 10
-1 10
+1 11
-1 11
1 12
=
-1 5
1 12
=
7 60
故答案为:
.7 60
答案解析:通过观察,每个分数的分母都可以写成两个连续自然数乘积的形式,分子都为1,因此,可把每个分数拆成两个分数相减的形式,然后通过加减相抵消的方法,求出结果.
考试点:分数的巧算.
知识点:完成此题,注意分数的拆分,通过加减相抵消的方法,求出结果.