# 11.6 Combinatorics: Combinations

Evaluate combination notation and solve related applied problems.

We now consider counting techniques in which order is not considered.

# Combinations

We sometimes make a selection from a set *without regard to order*. Such a selection is called a *combination*. If you play cards, for example, you know that in most situations the *order* in which you hold cards is not important. That is,

Each hand contains the same combination of three cards.

# Example 1

Find all the combinations of 3 letters taken from the set of 5 letters $\{\text{A},\text{}\text{B},\text{}\text{C},\text{}\text{D},\text{}\text{E}\}$.

# Solution

The combinations are

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