Q How many possible sets of 7 marbles are there?  
A The number of possible sets of 7 marbles is called C(10, 7). Other notations for it are  _{10}C_{7}  and 
 . 
Computing C(10, 7) by hand
1. Create a faction with 10 in the numerator and 7 in the denominator: 


2. Extend the term in the denominator to its factorial: 


3. Extend the term in the denominator to as many terms as in the denominator: 


4. Compute it (it helps to first cancel the terms in the denominator): 
 =  120 
C(5, 2) = 
 =  10  C(5, 5) = 
 =  1 
Some Special Cases:
Computation Utility:
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