I have used smaller numbers and the graph appeared to work. I post the test here below.

I have to use float point. I don’t know the max value an Mathematica type integer can hold. But pnp is an integer, but what I am comparing it too is not. It worked with smaller values. I thought that I could plot it and then use show to change the range. Thanks for the sample code I will try and use it.

I will use less than and greater than. I thought there was a calculation for this. Yes it is a float point comparison but is there no way to use some sort of analysis on the plot to find a given range. It would be invaluable if it were possible.

If I can read the graph, I can factor pnp in seconds.

pnp = 1847*2393

p3 = Plot[{((pnp^2 + x^3)/
pnp) - ((pnp + (x^2/(pnp^2 + x)) * pnp)) }, {x, 0, pnp}, 
PlotRange -> All]


p5 = Plot[{(pnp^2 + x^3)/pnp + (x^3/pnp)}, {x, 0, 1847}, 
PlotRange -> All]