I think the intended solution is $n=45,$ which can be easily found due to $45^2$ being well known to be $2025$, but $45^2 - \lfloor \sqrt{45} \rfloor$ produces $2019$ since $6.7$ rounds down to $6.$

peelybonehead wrote: I think the intended solution is $n=45,$ which can be easily found due to $45^2$ being well known to be $2025$, but $45^2 - \lfloor \sqrt{45} \rfloor$ produces $2019$ since $6.7$ rounds down to $6.$ Yes i think it is supposed to be n^2-$\lfloor \sqrt{n} \rfloor$=2019