Hello! I can definitely help you with that. You can use the TODAY() function in Excel to calculate the number of days since the last accident occurred. Here are the steps:

1. In a new cell, type in "=TODAY()" (without the quotes). This will give you today's date.
2. In another cell, type in "=MAX(A:A)" (without the quotes). This will give you the latest date in column A.
3. In a third cell, subtract the latest date from today's date using the formula "=TODAY()-MAX(A:A)" (without the quotes). This will give you the number of days since the last accident occurred.
4. Format the cell with the result as a number with no decimal places.

That's it! Now you have the number of days since the last accident occurred. You can also use conditional formatting to highlight the cell if the number of days exceeds a certain threshold, such as 30 days or 90 days. Let me know if you have any questions or need further assistance.