Let $L$ be the sum of all 3-digit numbers.
Let $K$ be the sum of all 3-digit numbers which are multiple of $13$.
Then $L=100+101+102+...+999=\frac{1099\times900}{2}=494550$
and $K=104+117+...+988=13(8+9+10+...+76)=\frac{13\times84\times69}{2}=37674$.
We are looking for $K-L=456876$