N Choose K Calculator n=2 result

Find out how many different ways you can choose k items from a set of n items without repetition and without order. This number is also called combination number or n choose k or binomial coefficient or simply combinations. See also general combinatorial calculator.

Elements to choose from:

(n)

Elements chosen:

(k)

Calculate

A bit of theory - the foundation of combinatorics

Combinations

A combination of the k-th class of n elements is an unordered k-element group formed from a set of n elements. The elements are not repeated and the order does not matter. In mathematics, such unordered groups are called sets and subsets. The count is called a combination number and is calculated as follows:

$C_k(n)=\left(\genfrac{}{}{0ex}{}{n}{k}\right)=\frac{n!}{k!(n-k)!}$

A typical example: we have 15 students and need to choose 3. How many ways can this be done?

Foundation of combinatorics in word problems

• Subsets
  How many are all subsets of set C = (97, 67, 66, 18, 59, 64)?
• Seating rules
  In a class, there are 28 seats, but in the 5.D class, there are only 24 students. How many ways can students sit? (The class has 14 benches. A bench is for a pair of students.) Result write down as powers of 10 - (logarithm - large number).
• Words
  How many 2 letters "words" are possible using 14 letters of the alphabet? a) without repetition b) with repetition
• Dice options
  We roll three dice. Write down all the feast options.
• Candy flavors
  A bag contains 20 candies in five different flavors: cherry, lemon, orange, mango, and cola. We know that there is at least one of each flavor in the pocket and that there are twice as many lemons as cherry ones. How many ways can different flavors be rep

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