I ended up using a helper column but got accomplished what I wanted to. I actually wanted to use the entire number instead of the 4 right digits (as throughout the year the number goes up until 18 becomes 19 at the first of the year). I just used the substitute function (eliminating the hyphen), changed to a VALUE, & then used whatever MAX/MIN function I wanted to & then used a custom format in the number to have it appear back has its original form.