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Evaluate the combination:

2C1

Combination Definition:

A unique order or arrangement

Combination Formula:

nCr  =  n!
  r!(n - r)!

where n is the number of items
r is the unique arrangements.

Plug in n = 2 and r = 1

2C1  2  2!
  1!(2 - 1)!

Factorial Formula:

n! = n * (n - 1) * (n - 2) * .... * 2 * 1

Calculate the numerator n!:

n! = 2!

2! = 2 x 1

2! = 2

Calculate (n - r)!:

(n - r)! = (2 - 1)!

(2 - 1)! = 1!

1! = 1

1! = 1

Calculate r!:

r! = 1!

1! = 1

1! = 1

Calculate 2C1

2C1  =  2
  1 x 1

2C1  =  2
  1

2C1 = 2


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Excel or Google Sheets formula:

Excel or Google Sheets formula:=COMBIN(2,1)

Common Core State Standards In This Lesson
HSS.CP.B.9
What is the Answer?
2C1 = 2
How does the Permutations and Combinations Calculator work?
Free Permutations and Combinations Calculator - Calculates the following:
Number of permutation(s) of n items arranged in r ways = nPr
Number of combination(s) of n items arranged in r unique ways = nCr including subsets of sets
This calculator has 2 inputs.

What 2 formulas are used for the Permutations and Combinations Calculator?

nPr=n!/r!
nCr=n!/r!(n-r)!

For more math formulas, check out our Formula Dossier

What 4 concepts are covered in the Permutations and Combinations Calculator?

combination
a mathematical technique that determines the number of possible arrangements in a collection of items where the order of the selection does not matter
nPr = n!/r!(n - r)!
factorial
The product of an integer and all the integers below it
permutation
a way in which a set or number of things can be ordered or arranged.
nPr = n!/(n - r)!
permutations and combinations
Example calculations for the Permutations and Combinations Calculator
Permutations and Combinations Calculator Video

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