title: Divide a number before formatting it inside a tooltip of Recharts
body: <p>I have this graph from recharts and it has a very long number in the tooltip:
   <a href="https://i.stack.imgur.com/XJLjq.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/XJLjq.png" alt="enter image description here"></a></p>
  
  <p>If I pass this property into the graph, it format the number well</p>
  
  <p><code>&lt;Tooltip formatter={maskString} /&gt;</code></p>
  
  <p>I'm using this function and NumberFormat from 'react-number-format';</p>
  
  <pre><code>export const maskString = (text) =&gt; {
    const hasThousandSeparator = true;
    const prefix = '$';
    return (
      &lt;NumberFormat
        value={text}
        displayType={'text'}
        thousandSeparator={hasThousandSeparator}
        prefix={prefix}
      /&gt;
    );
  };
  </code></pre>
  
  <p>The output is just what I need: 
  <a href="https://i.stack.imgur.com/p9XRF.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/p9XRF.png" alt="enter image description here"></a></p>
  
  <p>But before formatting the number, I need to divide it by 12... </p>
  
  <p>How can I do this?</p>