There are 24 students in a science class. Mr. Sato has given 9 pairs of students their 3 magnets. How many more magnets does Mr. Sato need some that each pair of students has exactly 3 magnets?
AS there are 24 students in the science class, there are 242=12 pair of students. Therefore number of pairs of students yet to be given magnets is 12−9=3 . For them he needs 3×3=9 magnets.
