Detailed explanation: the solutions of several other answers are correct, but they are more complicated. I have a very simple method here:

First of all, the square number of 1~9 must be clear. List 1, 4,9,16,25,36, 49,64,81.

Among these nine numbers, it is easy to find that the difference between 1 and 49 is 48; 16 and 64 also differ by 48.

The number of pieces is 1, 7 respectively; 4,8。 From the condition that "B buys 7 pieces more than A", it can be concluded that B has 8 pieces and A has 1 piece.

The solution to the problem now is to find the third square with a difference of 48.

According to the condition "A buys 9 more than B", if B is 1, A is 10, but 100-48 is not a square number; If b is 4, A is 13,169-48 =121is the square of 1 1. So B is 4 pieces and A is 13 pieces.

Now the answer is obvious.

One piece 13 pieces, 169 pieces.

B 8 pieces, 64 pieces

7 c, 49

One piece 1 piece 1 piece

B 4 pieces, 16

C 1 1 piece, 12 1 piece.