In engineering calculations, accuracy, limits, and approximation are used to represent a value. Consider two square blocks of different dimensions. The accurate values of their areas can be obtained by rounding off their numbers to the nearest values based on significant figures. Consider a right circular cone having a base radius, r, and height, h. If the cone is circularly sliced at a distance x from its vertex, such that the sliced element has a thickness, Δx, then its volume can be determined. By applying the limit from Δv to dv and Δx to dx, and neglecting higher-order differentials, the expression for the volume is obtained. Consider an arc AB, subtending a small angle at O. The arc-length can be approximated to a base of a right-angle triangle. If the length of the hypotenuse is unity, the arc-length equals sine theta, approximately equal to theta. In addition, cosine theta also approximately equals unity. For theta of one degree, the approximate value for sin theta and tan theta is nearly the same.