A customer recently asked me in the chat room how to make values that are ZERO not show up. For example, you're adding up a bunch of columns, and some of the columns are empty. You don't want a bunch of ZEROs to show up in the column footer when you do your SUM function. Here's how:

Highlight the cells you want to format. Right-click on them and select Format Cells. Click on the Number tab.

In the Category list, click Custom.

Now, in the Type box, enter in this text exactly as shown here:

0;-0;;@