n
=
10
∑
i
=
1
i
=
1
+
2
+
3
+
4
+
5
+
6
+
7
+
8
+
9
+
10
n
=
∑
i
=
1
10
i
=
1
+
2
+
3
+
4
+
5
+
6
+
7
+
8
+
9
+
10