Combination with Replacement Calculator

Calculate combinations with replacement (multichoose) for discrete mathematics and probability

Calculation Parameters

Number of distinct objects in the set
Number of elements to choose (with replacement)

Formula

CR(n,r) = (n + r - 1)! / (r! × (n - 1)!)
Also written as C(n+r-1, r)

Calculation Results

Enter values for n and r, then click "Calculate CR(n,r)" to see the combination with replacement result and step-by-step calculation.

Quick Examples

When to Use Combination with Replacement Calculator

Probability Problems

Calculate probabilities in scenarios where you can select the same item multiple times, such as drawing balls with replacement from an urn.

Discrete Mathematics

Solve combinatorial problems in discrete math courses, including multichoose problems and distribution of identical objects.

Statistics Analysis

Analyze sampling scenarios where replacement is allowed, useful in bootstrap sampling and statistical modeling.

Menu Selection

Calculate the number of ways to select items from a menu where you can choose the same item multiple times, useful for ordering systems.

Game Theory

Analyze game scenarios where players can make repeated choices from the same set of options, useful in strategic planning.

Resource Allocation

Determine the number of ways to distribute identical resources among different categories or departments with repetition allowed.

Frequently Asked Questions

What is a combination with replacement calculator?

A combination with replacement calculator computes the number of ways to choose r elements from a set of n distinct objects where order doesn't matter and repetition is allowed. It uses the formula CR(n,r) = (n+r-1)! / (r! × (n-1)!), also known as multichoose.

How does combination with replacement differ from regular combinations?

Regular combinations don't allow repetition of elements, while combinations with replacement allow selecting the same element multiple times. This makes CR(n,r) typically larger than C(n,r) for the same values, as you have more selection possibilities.

What is the formula for combinations with replacement?

The formula is CR(n,r) = (n+r-1)! / (r! × (n-1)!), where n is the number of distinct objects and r is the number of elements to choose. This can also be written as C(n+r-1, r) using the standard combination notation.

When do you use combinations with replacement?

Use combinations with replacement in probability problems where you can select the same item multiple times, such as drawing balls with replacement from an urn, selecting menu items where duplicates are allowed, or distributing identical objects into distinct groups.

What are some real-world applications?

Common applications include analyzing lottery systems, calculating probabilities in card games with replacement, determining menu selection possibilities, resource allocation problems, and statistical sampling scenarios where replacement is allowed.

Is this combination replacement calculator free?

Yes, our combination with replacement calculator is completely free to use. There are no limits on calculations, no registration required, and all features including step-by-step solutions are available at no cost.

What are the limitations of this calculator?

The calculator works with non-negative integers where n ≥ 1 and r ≥ 0. For very large values, results may be limited by JavaScript's number precision. The calculator provides exact results for most practical mathematical applications.

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