I have a spread sheet that calculates the Number of times an order is raised
by Supplier, the qyt's returned are quantity of orders raised with the last
12 months, within last 6 months and within last 3 months.

The data is taken from a seperate work sheet that tracks the Supplier name
(Column A) and Date of order (Column E) amongst other detail not relevent to
this formula.

I am using sum product but have exceeded 1000 orders therfore the formula
has stopped working. How else can i do this. Sum Product seem to run very
slow anyway