Lookup formula to detect change

Hi All

I need a formula that looks at whether there was a change in number and if there was what was the % change. I need this for last year, so will lookup C to N and also this year and so will look up O to Z. It also need to lookup Year to date, so therefore looking up the change from Jan to July if we were in Aug and then Jan to Aug if we were in Sept and so on..

I've attached an example for illustration, hope that makes sense

Thanks

Hi,

Not very sure, but try this:

for last year;

=(N3-C3)/C3

For This year:
=(INDEX($O$3:$Z$3,MONTH(TODAY())-1)-O3)/O3

Regards,