10. As shown in the right figure, there are six circles at the vertices of four small triangles. If six prime numbers are filled in these circles, their sum is 20, and the sum of the numbers at the three vertices of each small triangle is equal. What is the product of these six prime numbers?
10. 900
10.【Solution】Let the sum of the numbers at the three vertices of each small triangle be S. When the sum S of the 4 small triangles is added, each number at the vertices of the central triangle is counted 3 times, so: $4S = 2S + 20$, thus: $S = 10$. In this way, the three prime numbers at the vertices of each small triangle can only be 2, 3, 5, so the six prime numbers are $2, 2, 3, 3, 5, 5$, and their product is: $2 \times 2 \times 3 \times 3 \times 5 \times 5 = 900$