Sum of first n positive consecutive odd numbers is $n^2$.
1 + 3 + 5 (3 consecutive odd numbers) ➡ Sum = $3^2 = 9$
1 + 3 + 5 + 7 (4 consecutive odd numbers) ➡ Sum = $4^2 = 16$
Similarly, 20 consecuive odd numbers sum = $20^2 = 400$
So, if the first 20 consecutive positive odd numbers is divided by $20^2$, answer would be $\frac{20^2}{20^2}$ = 1