Answer:
21
Explanation:
√441
Take factors of 441
-> 1,3,7,9,21,49,63,147,441
If you know all of them like this and it’s an odd number, find the middle value that doesn’t have a pair and it’s 21.
If you don’t just take a different value that has a square root. Let’s do 9.
Separate the root into √9*49
Woah, both of those are squares!!
Take the square root of both of those numbers
√9*√49
3*7=21, voila.