Here's ten balls with number, from 1 to 10.
Total of the 10 balls' permutation:
〇〇〇〇〇〇〇〇〇〇
10P10 = 10!.
When divided into two each,
〇〇 〇〇 〇〇 〇〇 〇〇
10P2 8P2 6P2 4P2 2P2 = 10!.
When divided into three, three, four each,
〇〇〇 〇〇〇 〇〇〇〇
10P3 7P3 4P4 = 10!.
Total of the 10 balls' combination:
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10C10 = 1.
〇〇 〇〇 〇〇 〇〇 〇〇
10C2 8C2 6C2 4C2 2C2 / 5!.
〇〇〇 〇〇〇 〇〇〇〇
10C3 7C3 4C4 / 2!.