Malcom bought 24 glasses. This is because 9 divided by 3 equals 3. So that means it will be multipled by 3. So you need to multiply 8 by 3 and you get 24.
24 because if you just added 8 three times or multiplied 8*3, it would equal 24. you would multiply it by 3 because it would take him 3 sets of free plates to get 9 free plates.
