I think you mean DIV/0! This is a divide by zero error. The green triangle will be diplayed on any cell that doesn't pass the checking rules.
Answer: The formula cannot be calculated because there is an error.
Explanation: Excel checks a formula when you enter it. When a formula can’t be calculated, an error is displayed and a green triangle is added to the upper-left corner of the cell. For example, the formula =4/0 displays #DIV/0!. This displays because numbers can’t be divided by 0. You can select the cell with the error and click Error Checking to display a description of the error and a list of options... PF
