How to use SUMIF when using Conditional Formatting

That looks very interesting! I will study it later today or tomorrow and make sure I understand it properly. Do you know if the row numbers would adjust downwards automatically if I selected multiple rows?

Also, the stock will always be in the same multiple as the orders (e.g. 72), so the 150 scenario shouldn't ever happen (or the buyer of 78). It would be best to get the combination closest to total, but if this will allow me to drag down and use conditional formatting on a massive range of cells, then the time saving is worth the optimality.