Question 472664
nPr=permutation of n things taken r at a time.=n!/(n-r)!
4!/(4-3)!=4!=24
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Ed
.
123.
12.3
1.23
.123
132.
13.2
1.32
.132
213.
21.3
2.13
.213
231.
23.1
2.31
.231
312.
31.2
3.12
.312
321.
32.1
3.21
.321
.
The decimal point is the empty hook in each set of 4 numbers. It could be replace by 0 if you like. As you can see there are 24 ways just as the formula predicts.
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Ed