8. (10 points) On a plane, use toothpicks of length 6 cm to form squares. To form a square with a side length of 6 cm, 4 toothpicks are needed. To form 5 such squares, at least $\qquad$ toothpicks are needed.
【Answer】Solution: Arrange the toothpicks as shown in the figure below, the minimum number required can be achieved. According to the figure, at least 15 toothpicks are needed;

Answer: To form 5 such squares, at least 15 toothpicks are needed. Therefore, the answer is: 15.