Divide the group into two or more teams.
Assign a specific multiplication table to each team.
Appoint a leader.
Arrange teams in lines facing the chalkboard.

Upon signal,  the leaders walk to the board, write the first facts in their respective tables and pass the chalk to the next player. 

The game continues, relay-style, until one team completes its table.
When an incorrect fact is written, the team members rub their own heads .
The next player must correct the error before adding an entry.

The winning  team is the first one producing a perfect table.