title: Updating any cell from a formula in Excel 2010
body: <p>Say I have the formula: <code>V = IR</code></p>
  
  <p>In Excel, I need to calculate any of the combinations of this possible.</p>
  
  <p>For example,</p>
  
  <ul>
  <li>if I am given the value of I and R, I would need to display the result of V in the cell in which I have V (user keeps it 0 or blank to denote that's the value he wants to find out)</li>
  </ul>
  
  <p>Excel sheet before:</p>
  
  <pre><code>+------+---------+------+
  | V    |   I     |   R  |
  +------+---------+------+
  | 0    |   1     |   10 |
  +------+---------+------+
  </code></pre>
  
  <p>Excel sheet after:</p>
  
  <pre><code>+------+---------+------+
  | V    |   I     |   R  |
  +------+---------+------+
  | 10   |   1     |   10 |
  +------+---------+------+
  </code></pre>
  
  <ul>
  <li>if I am given the value of V and R, I would need to display the result of I in the cell in which I have I (user keeps it 0 or blank to denote that's the value he wants to find out)</li>
  </ul>
  
  <p>Excel sheet before:</p>
  
  <pre><code>+------+---------+------+
  | V    |   I     |   R  |
  +------+---------+------+
  | 10   |   0     |   10 |
  +------+---------+------+
  </code></pre>
  
  <p>Excel sheet after:</p>
  
  <pre><code>+------+---------+------+
  | V    |   I     |   R  |
  +------+---------+------+
  | 10   |   1     |   10 |
  +------+---------+------+
  </code></pre>
  
  <p>Coding a function to check if a cell is 0 and updating another "answer" cell (besides V, I, R; this cell calls this function explicitly) with the expected value is no issue.</p>
  
  <p>The challenge is in having the blank cell (value that we need to calculate from the other variables provided) update besides the extra "answer" cell.</p>
  
  <p><strong>Excel does not allow a formula to update any cell</strong>, and this will require some workaround - which I cannot think of.</p>
  
  <p>How do I make this work?</p>