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      <text>37.1.1.5 General permutation take r at a time</text>
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      <text><![CDATA[<p>In general the numbers of permutations of <span class="math inline">\(n\)</span> objects taken <span class="math inline">\(r\)</span> at a time is <br>\(\qquad n(n-1)(n-2)\dots (n-r+1)\qquad \) which is the same as \(\displaystyle{\quad\frac{n!}{(n-r)!}}\)
<br>This is usually denoted by <span class="math inline">\(^nP_r\)</span> so that&nbsp; &nbsp;<span class="math inline">\[\displaystyle{\qquad ^nP_r=\frac{n!}{(n-r)!}}.\]</span>&nbsp;If we allow repetitions the number of permutations becomes <span class="math inline">\(n^r\)</span> (can you see why?).</p>]]></text>
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