If the word has seven distinct letters, you have 7! = 5040 ways of arranging them (simple permutations of seven items). However, if some letters appear more than once, the number of arrangements gets reduced! For instance:
If the word is "WITNESS", we have "S" appearing twice, so we divide 7! by 2! = 2 and the result is 2520.
If the word is "SOMEONE", we have "O" and "E" appearing twice, so we divide 7! by 2! * 2! = 4 and the result is 1260.
If the word is "UNKNOWN", we have "N" thrice, so we divide 7! by 3! = 6 and the result is 840.
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