title: Loop through the sheets and calculate the sum using VBA
body: <p>In Excel , I have to add the time allocated to different departments per month and also annually.So the excel has sheets 12 sheets that are from January to December. It looks like this : (Jan)
  <a href="https://i.stack.imgur.com/RZ2iC.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/RZ2iC.png" alt="January Sheet"></a></p>
  
  <p>The same is repeated for other months of the year.But the time allocated may be different and some departments may not be mentioned at all.</p>
  
  <p>The task is I have to do is to add all the time effort allocated to different departments in different months and show it on a sheet.
  Something along the line :</p>
  
  <p><a href="https://i.stack.imgur.com/6DmVl.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/6DmVl.png" alt="Time Effort for different months"></a></p>
  
  <p>And at last in another sheet, I have to add all the time effort for different departments for the whole year.
  Something along the line:</p>
  
  <p><a href="https://i.stack.imgur.com/cyC3s.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/cyC3s.png" alt="Time effort for the whole year"></a></p>
  
  <p>I was wondering is there a way I could achieve this using VBA scripting.Kindly help.</p>