title: how to add formula to a column contains values
body: <p>for example, in column A, I have a 500 cells (A1:A500) that contain values, and I need to add up column A : column C without creating a new column because i need to show the orignal column A values within the formula, </p>
  
  <p>eg:</p>
  
  <p>A1 = 753; B1 = -100; C1 = 200</p>
  
  <p>I need a formula in A1 become ==> A1 = +753+B1+C1</p>
  
  <p>I need to show the calculation logic within the formula by keeping the column A values</p>
  
  <p>how can i do without manually add the formula each cell?</p>
  
  <p>Thanks in advance</p>