How to color a cell in Google spreadsheets if its value is a multiple of 8?

Question

Google Sheets

Hello, I am doing crm to track visits in Google spreadsheets (test sheet "2nd junior")

How to implement the task that a person left 8 classes (scored 8 units), and this was somehow indicated visually.
As an idea, just add ones, and see if the number is a multiple of 8, but how to visually implement this? And even better, if there are 7 visits since the last payment, then in yellow, if 8, then in orange, if 9 or more, then in red, but if a person has paid, then the counter resets the color.

Answer 1

For a range , a
A6:A
custom formula
=AND(NOT(ISBLANK($A6));MOD(SUM($D6:$AB6);8)=0)