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      <text>37.1.1.4 Example permutations take r at a time</text>
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      <text><![CDATA[<hr>
<h4 class="HELM_example">Example</h4>
<p>Find the number of permutations of the four letters \(A, B, C\) and \(D\) taken three at a time.</p>
<h4 class="HELM_solution">Solution</h4>
<p>We may choose the first letter in 4 ways, either <span class="math inline">\(A, B, C\)</span> or <span class="math inline">\(D\)</span>. Suppose, for the purposes of illustration we choose <span class="math inline">\(A\)</span>. We may choose the second letter in 3 ways, either <span class="math inline">\(B, C\)</span> or <span class="math inline">\(D\)</span>. Suppose, for the purposes of illustration we choose <span class="math inline">\(B\)</span>. We may choose the third letter in 2 ways, either <span class="math inline">\(C\)</span> or <span class="math inline">\(D\)</span>. Suppose, for the purposes of illustration we choose <span class="math inline">\(C\)</span>. The total number of choices made is <span class="math inline">\(4\times 3\times 2=24\)</span>.</p>]]></text>
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