想請問排列組合的問題
Q: How many ways can 16 different gifts be divided among 4 children such that each child receive exactly 4 gifts?
A: 16! / (4!)^4
Q: How many ways can 3 identical green shirts and 3 identical red shirts be distributed among 6 children such that each child receive a shirt?
A: 20
我想法是 6! / 6*6 ？
兩題分子部分ok
但分母還請各位指教 應該是怎麼想？