Appologies, I'm no mathematician, so I don't even know what words to google to find equations. This is likely simple math.
I need to create a formula in a program that for an input of 1 I can get a result, As an example 50, but for 2 I get a result approx 75, and 3 might be 95, etc, and I can structure it so the last result of 500 might result in 500. I'm sure this is simple, yet I don't know what its called to even google it.
Thanks in advance, I only need the name so I can google it, but will happily discuss further if interested.
If I understand your question correctly, you want a continuous function that "increases with smaller increments" for greater inputs?
A simple exponential function might fit your application:
The curve above is an arbitrarily picked exponential function that roughly matches the model you described:
$$y=-e^{\left(\frac{500-x}{80}\right)}+500$$
Since you said wanted a name that you can google, consider following up on the keywords
Exponential models are trivial to incorporate into programs (the application you mentioned in your question). Most modern languages include built-in or library support for exponentiation. For instance, in Python you have the exponential operator
**and the functionmath.exp. Java includesjava.lang.Math.{exp,pow}, etc.