\(\dfrac{19981998}{20202020}=\dfrac{19981998:10001}{20202020:1001}=\dfrac{1998}{2020}=\dfrac{1998:2}{2020:2}=\dfrac{999}{1010}\)
\(\dfrac{19981998}{20202020}\)=\(\dfrac{19981998:10001}{20202020:10001}\)=\(\dfrac{1998}{2020}\)=\(\dfrac{1998:2}{2020:2}\)=\(\dfrac{999}{1010}\)