Who is asking: Student
I drew a diagram to see what Clyde was doing.
Now I understand. He is making a square of clovers in each set. In the next set (the 4th set) he will have a square arrangment of 4 clovers by 4 clovers. Thus in this set there will be 4 x 4 = 16 clovers. Can you finish the problem now?