**Instructions:**

- Enter 'n' (total items) and 'r' (selection count).
- Check "Allow Zero Selection" if needed.
- Click "Calculate" to compute the result.
- View the result and calculation details below.
- Use "Calculation History" to track previous calculations.
- Click "Clear" to reset the inputs and results.
- Click "Copy Result" to copy the result to the clipboard.

**Advanced Features**

**Result:**

**Calculation Details**

**Calculation History**

Calculation | Result |
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The Combination with Replacement Calculator is a tool that helps you calculate the number of possible combinations that can be obtained by taking a subset of items from a larger set. This calculator is useful when you need to choose a sample of r elements from a set of n distinct objects where order does not matter and replacements are allowed.

## Concepts

### Combinations

The number of ways to choose a sample of r elements from a set of n distinct objects where order does not matter and replacements are not allowed is called a combination. The formula for calculating the number of combinations is:

C(n,r) = n! / (r! * (n-r)!)

### Combinations with Replacement

The number of ways to choose a sample of r elements from a set of n distinct objects where order does not matter and replacements are allowed is called a combination with replacement. The formula for calculating the number of combinations with replacement is:

CR(n,r) = (n + r – 1)! / (r! * (n – 1)!)

### Factorial

The factorial of a non-negative integer n, denoted by n!, is the product of all positive integers less than or equal to n. For example, 5! = 5 x 4 x 3 x 2 x 1 = 120.

## Formulae

The formula for calculating the number of combinations with replacement is:

CR(n,r) = (n + r – 1)! / (r! * (n – 1)!)

## Benefits

The Combination with Replacement Calculator has several benefits, including:

- It saves time by quickly calculating the number of possible combinations.
- It eliminates the need for manual calculations, which can be prone to errors.
- It provides accurate results every time.

## Interesting Facts

- The Combination with Replacement Calculator is also known as the multichoose calculator.
- The calculator can be used in various fields, including mathematics, statistics, and computer science.
- The concept of combinations with replacement is used in probability theory and combinatorics.

## Use Cases

The Combination with Replacement Calculator can be used in various scenarios, including:

- In probability theory, it can be used to calculate the probability of an event occurring when there are multiple outcomes.
- In computer science, it can be used to generate all possible combinations of characters in a password.
- In statistics, it can be used to calculate the number of ways that a sample can be drawn from a population.

**References**

Here are some references that provide more information on combinations and binomial coefficients:

- Kenneth H. Rosen: Discrete Mathematics and Its Applications, 8th Edition, McGraw-Hill Education, 2019
- Susan S. Epp: Discrete Mathematics with Applications, 5th Edition, Cengage Learning, 2018
- Thomas H. Cormen, Charles E. Leiserson, Ronald L. Rivest, and Clifford Stein: Introduction to Algorithms, 3rd Edition, MIT Press, 2009

Last Updated : 25 November, 2023

Emma Smith holds an MA degree in English from Irvine Valley College. She has been a Journalist since 2002, writing articles on the English language, Sports, and Law. Read more about me on her bio page.