Question 16
Let $n$ be the least integer satisfying
$$n\gt 1000,\qquad \gcd(63,n+120)=21,\qquad \gcd(n+63,120)=60.$$
What is the sum of the digits of $n$?
$$n\gt 1000,\qquad \gcd(63,n+120)=21,\qquad \gcd(n+63,120)=60.$$
What is the sum of the digits of $n$?