title: How to make a calculator in Excel that has 3 cells, and when any 2 are filled the remaining one gets calculated?
body: <p>For example, a speed-distance-time calculator.</p>
  <p>Since Distance = Speed x Time,</p>
  <p>There are 3 cells, one each for D, S, and T.</p>
  <p>Filling any 2 of these 3 values, the other one gets calculated automatically.</p>