Dictionary A B C D E F G H I J K L M N O P Q R S T U V W X Y Z sector A piece of an object. In the spinner, any of the numbered segments is a "sector" (cf From Geometry to Probability Discussion). self-similarity Two or more objects having the same characteristics. In fractals, the shapes of lines at different iterations look like smaller versions of the earlier shapes (cf Self-Similarity Discussion). sequence An ordered set whose elements are usually determined based on some function of the counting numbers. set A set is a collection of things, without regard to their order (cf Internet Search and Set Operations Discussion). significant digits The number of digits to consider when using measuring numbers. There are three rules in determining the number of digits considered significant in a number. 1) All non-zeros are significant. 2) Any zeros between two non-zeros are significant 3) Only trailing zeros behind the decimal are considered significant slope of the linear function The slope of the line y = mx + b is the rate at which y is changing per unit of change in x. The units of measurement of the slope are units of y per unit of x (cfLinear Functions Discussion). square A parallelogram with four congruent sides and four right angles (cfRectangle Discussion). standard deviation Standard deviation tells how spread out numbers are from the average, calculated by taking the square root of the arithmetic average of the squares of the deviations from the mean in a frequency distribution (cf The Normal Distribution Discussion). subset A subset of a given set is a collection of things that belong to the original set. For example, A={a,b} could include, a, b, a and b, or the null set (neither). subtraction The operation in which the difference between two numbers or quantities is calculated. Also, the inverse of addition (cf Integer Addition and Subtraction Discussion, Fraction Adding and Subtracting Discussion). superscript In mathematics, superscripts are numbers or letters written above and to the right of other numbers or letters or symbols indicating how many times the latter is to be used as a factor. When typing, one can represent a superscript by using the ^ symbol to indicate raising the number. For example, x3 is the same as x^3, which equals x * x * x (cf Trees as Data Structures Discussion). surface area A measure of the number of square units needed to cover the outside of a figure (cfSurface Area and Volume Discussions). symmetry The correspondence in size, form, or arrangement of parts on a plane or line. In line symmetry, each point on one side of the line has a corresponding point on the opposite side of the line (picture a butterfly, with wings that are identical on either side). Plane symmetry refers to similar figures being repeated at different but regular locations on the plane (cfSymmetry in Tessellations Discussion). A B C D E F G H I J K L M N O P Q R S T U V W X Y Z