You are correct, Teach.
However, you don't need the middle number, the phosphorus, its expensive, (and phos is outlawed in some states).
And they didn't even tell you that slow release nitrogen is far superior: it resists wash out due to heavy rain, and it lasts longer--so you don't need as much. Try to find a higher quality nutritional product. It should have about 50 percent of the nitrogen in the form of slow release.
In Springfield your soil may be high quality. Perhaps you don't really need the last number either (potassium, also expensive).
Perhaps 37-0-0 fully coated is the best bet.
If your soil potash is 120 lbs/acre or more--you don't need more.