title: Modulus in Casio fx991es
body: <p>I recently found a way here on stackoverflow to calculate modulus using the fx991es. It must be configured to use radiants in order to make this work.</p>
  
  <pre><code>Pol(-Rec(1/(2π) , 2π×A/B), Y)(π - Y)B
  </code></pre>
  
  <p><a href="https://stackoverflow.com/questions/8419981/how-to-calculate-a-mod-b-in-casio-fx-991es-calculator">How to calculate a Mod b in Casio fx-991ES calculator</a></p>
  
  <p>However I do not really understand how this works. I see that its some math-hack using polar coordinates and stuff. But why does this actually work?</p>