title: Compressing big number (or string) to small value
body: <p>My ASP.NET page has following query string parameter:</p>
  
  <pre><code>…?IDs=1000000012,1000000021,1000000013,1000000022&amp;...
  </code></pre>
  
  <p>Here <code>IDs</code> parameter will always have numbers separated by something, in this case <code>,</code>. Currently there are 4 numbers but normally they would be in between <code>3</code> and <code>7</code>. </p>
  
  <p>Now, I am looking for method to convert each big number from above into smallest possible value; specifically compressing value of <code>IDs</code> query string parameter. Both, compressing each number algorithm or compressing whole value of <code>IDs</code> query string parameter are welcome.</p>
  
  <ol>
  <li>Encode or decode is not an issue; just compressing the value <code>IDs</code> query string parameter.</li>
  <li>Creating some unique small value for <code>IDs</code> and then retrieving its value from some data source is out of scope.</li>
  </ol>
  
  <p>Is there an algorithm to compress such big numbers to small values or to compress value of the <code>IDs</code> query string parameter all together?</p>