Hope you guys can help! 

I have a list of projects ranked 1-28. If a new project is entered and the rank is set at #8, I would like all the following numbers to be adjusted. (i.e. original #8 becomes #9, original #9 becomes #10...).  

Is there a clean way to accomplish this? Field type is "number" currently. Hoping to find a formula but that might not work.