Ta có:
\(\frac{2001.2002+2003.21+1981}{2002.2003-2001.2002}=\frac{2001.2002+2002.21+21+1981}{2002.\left(2003-2001\right)}\)
=\(\frac{2002.\left(2001+21\right)+2002}{2002.2}=\frac{2002.2022+2002}{2002.2}\)
=\(\frac{2002.\left(2022+1\right)}{2002.2}=\frac{2002.2023}{2002.2}\)
=\(\frac{2023}{2}\)