The largest digit is $5$, and the smallest digit is $0$.  $5-0=5$ 
The last four digits in Andy\textquotesingle s ID card are $2025$. What is the the difference between the largest and the smallest digit in $2025$?~(adapted from $$2011$$ Math kangaroo Problems, Level $$1-2$$, Question \#$$7$$) 
$$2$$ 
$$3$$ 
$$4$$ 
$$5$$ 
$$0$$ 