The third series comprised five episodes focusing on division by particular amounts .
The third series was again produced in 1997 after the BBC 's corporate change ( as evidenced by the then - new BBC logo at the end of each episode ) .
The third series , which was again produced in 1997 after the BBC 's corporate change ( as evidenced by the then - new BBC logo at the end of each episode ) , comprised five episodes focusing on division by particular amounts .