Conditional format formula to select a previous cells content (current cell -1)

Question

Thanks to "Can Google Spreadsheets conditionally format based on a previous cells content?", I understand how to apply conditional formatting to a preceding cell, if I'm using a simple comparison, but what about something more complicated.

For example I have data in a column in the following format:

B4                 | C4
--------------------------------------
123 / clientname1  | 143 / clientnamea
345 / clientname2  | 143 / clientnameb

With a one off formula, below, I can split and compare the two numbers:

=(TRIM(LEFT($C4,(SEARCH("/", $C4))-1)))-(TRIM(LEFT($B4,(SEARCH("/", $B4))-1))) > 0

However, how would I create a reusable rule that uses something along the lines of 'current cell - minus - value one cell left', rather than hardcoding $C4, $B4 etc each time?

Answer 1

The answer to the question you linked contains the answer to this one. But since it apparently didn't get through, here it is again:

In conditional formatting, you enter the formula as it should apply to the upper left corner of the formatted range. The spreadsheet will apply it to the rest of the range using relative references. So, if the upper left corner of formatted range is C4, then

• =B4 means "the value in the cell to the left of this one".
• =$B4 means "the value of the cell in B column of this row"
• =C$1 means "the value at the top of this column"
• =$B$2 means "the value in cell B2"