What is the maximum no of bags will I need to place 15 marbles if each bag can hold 6 marbles?

The maximum number of bags would be three.
One bag=6 marbles
Two bags=12 marbles
Three=18 marbles.
The third bag is used to fit the leftover marbles that the second bag couldn't fit.You won't need to use up all the space,so the three leftover can be placed into the third bag.