Square roots can't be really be explained, but there is one think you should know. 422 is 22 more than 400, which is greater than what would be the halfway point (20.5 ^ 2 = 420.25), so √422 is greater than 20.5, but not greater than 20.55 (20.55 ^ 2 = 422.3025). However, it is close to 20.55 though. Thus, you can conclude √422 is about 20.5426.
