Question 1173647
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This number is  {{{4!/2!}}} = {{{24/2}}} = 12.


In the denominator, 2! is standing to account for two repeating letters " S ".
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Solved.


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See the lesson

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF =https://www.algebra.com/algebra/homework/Permutations/Arranging-elements-of-sets-containing-undistinguishable-elements.lesson>Arranging elements of sets containing indistinguishable elements</A>

in this site.