How many games are in the Portal series?
2
3
3
3
3
3
3
2
3
2
3
4
2
3
4
2
3
4
2
3
5
1
4
2
3
5
1
4
2
3
5
1
4
2
3
5
1
4
2
3
5
1
4
2
3
5
1
4
2
3
5
1
4
2
3
5
1
4
2
6
0
3
7
5
1
4
2
6
0
3
7
5
1
4
2
6
7
5
0
1
4
2
6
7
5
1
4
2
6
0
7
5
1
4
2
6
0
7
5
1
4
2
6
7
5
0
1
4
2
6
9
7
5
1
4
6
0
9
7
5
1
4
6
8
0
9
7
5
1
6
8
9
7
5
0
1
6
8
9
7
5
1
6
8
9
7
6
8
9
7
6
8
9
7
6
8
9
7
10
6
3 games
8
9
7
10
6
8
9
7
10
6
8
9
7
10
6
8
9
7
11
10
8
9
ten
13
11
3 games
10
8
9
13
11
10
ten
2 games
14
8
9
13
11
10