The ability to round a number to a number of decimal places or to a number of significant figures is essential if answers are to be written to the correct degree of accuracy asked for in a question.

The radius of a circle or a sphere is the distance between the center and the edge. The radius can be used to calculate a circle's diameter, area and circumference. Likewise, a sphere's volume is ...

If two secants are drawn to a circle from an external point, then the product of the length of one secant segment and its external segment equals the product of the length of the other secant segment ...