What is Ohio State's record against Illinois? Record by decade?
How many points has Ohio State scored against Illinois? What is the average score when the game is played in Columbus?
What is Ohio State's record against Illinois when the Buckeyes are ranked and the Illini are not ranked?
You can find those answers and quite a bit more by reading The Series History: Ohio State/Illinois.
Sorry to leave a link and not re-post, but the original post went to blog heaven and it took a long time to create. Unfortunately copy/paste does not work with tables.