That's the number known as "twenty factorial".
When rounded to the nearest billion, it's 2,432,902,008,000,000,000 .
6, 10, 11, 12, 14, 14, 15, 22 mean: 13 median: 13 mode: 14 range: 16
11
11
13 14 12 10 11 9
8
(4*10+11+2*12+13+2*14)/10 = 11.6
10 7 11 12 9 13 14 11 15 16 13 17 18 15 19 20...
7, 10, 11, 12, 13, 14, 17
11
6, 10, 11, 12, 14, 14, 15, 22 mean: 13 median: 13 mode: 14 range: 16
10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20
11
11
11.
11
11
The answer is 15 because the pattern is subtract one, add two