2
3
4
5
6
7
8
9
10
11
12
2
3
4
5
6
7
8
9
10
11
12
12
11
10
9
8
7
6
5
4
3
2
12
11
10
9
8
7
6
5
4
3
2
1x
1
2x
3
3x
6
4x
10
5x
15
6x
21
7x
28
8x
36
9x
45
10x
55
11x
66
12x
78
+
+
+
-
=