SOLUTION: In how many ways can 6 letters be chosen from {R,S,T,U,V,W,X,Y,Z}, assuming that the order of the choices doesn't matter and that repeats are not allowed?

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Question 889970: In how many ways can 6 letters be chosen from {R,S,T,U,V,W,X,Y,Z}, assuming that the order of the choices doesn't matter and that repeats are not allowed?
Answer by Edwin McCravy(20054) About Me  (Show Source):
You can put this solution on YOUR website!
9 Choose 6 = 9C6 = C(9,6) = %28matrix%282%2C1%2C9%2C6%29%29 = 84

= 9%21%2F%286%21%289-6%29%21%29 = 9%21%2F%286%213%21%29 = %289%2A8%2A7%2A6%2A5%2A4%2A3%2A2%2A1%29%2F%28%286%2A5%2A4%2A3%2A2%2A1%29%283%2A2%2A1%29%29 =
  
  3  4
 =  3*4*7 = 84

On a TI calculator

Press ON
Press CLEAR
Press 9
Press MATH
Press left arrow key <
Press 3
Press 6        See:   9 nCr 6
Press ENTER    See:        84

Edwin