Here is a common scenario for me. I like to apply alternate line formatting on spreadsheets, especially wide spreadsheets. It makes it easier to follow the correct row across the spreadsheet. Here a blue fill is applied to alternate lines.

But in this spreadsheet, I wanted to do something a little different. I wanted the alternate line formatting only be applied once the date is entered.

This means I need to find the last row in the date column. Now previously I’ve used a COUNTIF formula, to count the number of rows with data. Then subtract any blank rows at the top of the spreadsheet. The drawback of this formula, is that editing the spreadsheet later often means the COUNTIF is no longer correct. Gaps in the data also cause problems.

# Enter the AGGREGATE Function

The AGGREGATE function was introduced in Excel 2010. Bill Jelen called it *“SUBTOTAL on steroids”*. It offers 8 more functions than SUBTOTAL and the ability to ignore hidden rows and error values. You can use it either in a Reference or Array form. Here is a link to the MS Support article. One of the new functions offered is LARGE.

So this formula uses

*=AGGREGATE(14,6,ROW(A:A)/(NOT(ISBLANK(A:A))),1)*

14 – refers to the LARGE function

6 – tells it to ignore error values

ROW(A:A)/(NOT(ISBLANK(A:A))) creates an array of the results of each row number in column A divided by whether the NOT(ISBLANK) portion of the formula returns a TRUE or FALSE answer. TRUE is evaluated as 1 and FALSE as 0. As division by zero creates an error, any blank cells are ignored.

1 – indicates that the LARGE function will return the largest number from the array. Hence, the last row.

# And things came to a grinding halt…

At this point, I did what I normally do and made my AGGREGATE formula into a Named Formula. I typically find this is to be a tidier way of working. When I did this; Excel froze. Repeatedly. Whenever, I did anything that caused a recalculation. Like clicking on a formula to examine it. And if I persisted and used the named formula in the Conditional Formatting formula … things … just … slowed … down … more.

But interestingly, the performance of the spreadsheet doesn’t appear to be affected when the formula is placed in a cell. I was working in Office 2016. I’ll test it later in Office 365, and report back if I get different results. I actually caused the same freezing problem by using the Evaluate Formula button. Excel slows right down as it creates the array of every cell in column A divided by NOT(ISBLANK). Somehow, however, when the formula is in a cell – Excel manages to handle the calculation much more efficiently. I even checked by making the reference to the formula into a named range. No problems. So, if you are planning to use the AGGREGATE function in this way, you’ll need to actually place it somewhere in the spreadsheet. Oh, and you will need to make that cell into a Named Range or else the Conditional Formatting Formula will not work (that was kinda unexpected).

# The Conditional Formatting Formula

The formula to produce this conditional formatting is:

*=AND(ROW()<=Last_Row,MOD(ROW(),2)=1)*

Last_Row refers to cell $B$2

This checks to see if the current row number is less than or equal to the value in the Last_Row Named Range AND if it is an odd numbered row, if so a blue fill is applied.

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