You have 8 balls. You can fit more than one in each pan so start with 4 on each side. This weight 1. You will see one side weighs more. Remove the 4 lessor balls. Now divide the pan into 2 balls on each side. This is weight 2. Again, one side will weigh more. Remove the 2 balls and divide the last 2 balls onto each side. This is weight 3, which will generate your answer to which ball is heavier.