problem solving - the thought processes involved in solving a problem

extrapolation - (mathematics) calculation of the value of a function outside the range of known values

interpolation - (mathematics) calculation of the value of a function between the values already known

conversion - a change in the units or form of an expression: "conversion from Fahrenheit to Centigrade"

approximation, estimate, estimation, idea - an approximate calculation of quantity or degree or worth; "an estimate of what it would cost"; "a rough idea how long it would take"

derivative, derived function, differential, differential coefficient, first derivative - the result of mathematical differentiation; the instantaneous change of one quantity relative to another; df(x)/dx

integral - the result of a mathematical integration; F(x) is the integral of f(x) if dF/dx = f(x)