Enter n

Enter r

  

Evaluate the combination:

24C2

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 = 24 and r = 2

24C2  2  24!
  2!(24 - 2)!

Factorial Formula:

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

Calculate the numerator n!:

n! = 24!

24! = 24 x 23 x 22 x 21 x 20 x 19 x 18 x 17 x 16 x 15 x 14 x 13 x 12 x 11 x 10 x 9 x 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1

24! = 620,448,401,733,239,409,999,872

Calculate (n - r)!:

(n - r)! = (24 - 2)!

(24 - 2)! = 22!

22! = 22 x 21 x 20 x 19 x 18 x 17 x 16 x 15 x 14 x 13 x 12 x 11 x 10 x 9 x 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1

22! = 1,124,000,727,777,607,680,000

Calculate r!:

r! = 2!

2! = 2 x 1

2! = 2

Calculate 24C2

24C2  =  620,448,401,733,239,409,999,872
  2 x 1,124,000,727,777,607,680,000

24C2  =  620,448,401,733,239,409,999,872
  2,248,001,455,555,215,360,000


24C2 = 276


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Excel or Google Sheets formula:

Excel or Google Sheets formula:=COMBIN(24,2)

Common Core State Standards In This Lesson
HSS.CP.B.9
What is the Answer?
24C2 = 276
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)!
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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