125. There are 60 squares, each with a side length of 1 cm. From these squares, all possible rectangles are formed, each using all 60 squares. Find the sum of the areas of all these rectangles.

## Answers. Solutions
125. From 60 squares, rectangles of the following sizes can be obtained: $60 \times 1, 30 \times 2, 15 \times 4, 20 \times 3, 12 \times 5, 10 \times 6$, i.e., a total of 6 different rectangles. The area of each of them is 60 cm $^{2}$. Then the sum of the areas of all the rectangles will be $360 \mathrm{~cm}^{2}$.