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 factor Any of the numbers or symbols in mathematics that when multiplied together form a product. For example, 3 is a factor of 12, because 3 can be multiplied by 4 to give 12. Similarly, 5 is a factor of 20, because 5 times 4 is 20 (cf What are Multiples Discussion). Fibonacci numbers A set of numbers formed by adding the last two numbers to get the next in the series: 0, 1, 1, 2, 3, 5, 8, 13. Named for Leonardo of Pisa, an Italian mathematician of the Middle Ages, who called himself Fibonacci, short for filius Bonacci which means "son of Bonacci". The original problem he investigated in1202 A.D. was about how fast rabbits could breed under ideal circumstances. His research led to the construction of this unique set of numbers (cf Recursion Discussion). fractal Term coined by Benoit Mandelbrot in 1975, referring to objects built using recursion, where some aspect of the limiting object is infinite and another is finite, and where at any iteration, some piece of the object is a scaled down version of the previous iteration (cf Properties of Fractals Discussion, also Plane Figure Fractals Discussion). fraction A rational number of the form a/b where a is called the numerator and b is called the denominator (cfFractions Discussion, Percents Discussion). frequency The number of items occurring in a given category. frequency view An approach taken by mathematicians and scientists to determine the chances of an event happening by repeating the experiment many times and using the results to calculate the probability. See theories of probability (cf Probability vs. Statistics Discussion). function A function f of a variable x is a rule that assigns to each number x in the function's domain a single number f(x). The word "single" in this definition is very important (cf Functions as Processes or Rules 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