Math calculation/autocomplete plugin?

Let's say I have some code where I have an integer and I need to change it - but I don't know what I need to change it to, I just know that I need to increase it by 26% or some other arbitrary math.

Is there anything out there where I could just select the value and feed it a basic calculation, or maybe type in a math operation and autocomplete recognizes that it can condense that down to the resulting value?

I don't know if this would be something currently available as a plugin or not, but curious to know if this functionality exists anywhere.