Square of a number with a trailing digit

For a number ending in $5$, multiply the leading part by its successor.

1. Write $195=10\times 19+5$.
2. Use $(10n+5{)}^2=100\times n\times (n+1)+25$ with $n=19$.
3. Compute $19\times 20=380$, so the leading part is $38000$.
4. Append the $25$: $38000+25=38025$.

Answer: $38025$