In many practical applications, we are interested in the values of the quantities y1, ..., ym which are difficult (or even impossible) to measure directly. A natural idea to estimate these values is to find easier-to-measure related quantities x1, ..., xn and to use the known relation to estimate the desired values yi. Measurements come with uncertainty, and often, the only thing we know about the actual value of each auxiliary quantity xi is that it belongs to the interval [Xi − Δi, Xi + Δi], where Xi is the measurement result, and Δi is the upper bound on the absolute value of the measurement error Δ xi = Xi − xi. In such situations, instead of a single value of a tuple y = (y1, ..., ym), we have a range of possible values. In this paper, we provide calculus-based algorithms for computing this range.