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 decimal number A fraction where the denominator is a power of ten and is therefore expressed using a decimal point. For example: 0.37 is decimal equivalent of 37/100 (cfDecimals Discussion). degrees A circle is measured in units called degrees. The entire circle is 360 degrees, half a circle is 180 degrees, and one quarter of a circle is 90 degrees. The "L" shaped 90 degree circle forms what is called a right angle. When examining circular objects, such as spinners, the size of each segment in the circle can be described in degrees (cf From Geometry to Probability Discussion). denominator In a rational number, the number below the fraction bar that indicates what kind of parts there are. See also numerator (cfFractions Discussion, Adding and Subtracting Fractions Discussion, Multiplying and Dividing Fractions Discussion, Comparing Fractions Discussion, and Percents Discussion). discontinuous graph A line in a graph that is interrupted, or has breaks in it forms a discontinuous graph (cf Impossible Graphs Discussion). disjoint events Two events are disjoint if they can't both happen at the same time (in other words, if they have no outcomes in common). Equivalently, two events are disjoint if their intersection is the empty set. domain of the function f The set of numbers x for which f(x) is defined. 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 Please direct questions and comments about this project to Addison-Wesley math@aw.com © Copyright 1997-2001 The Shodor Education Foundation, Inc. © Copyright 2001 Addison-Wesley. All rights reserved.