Title 
Description 

Face, Geometry 
Solids, in geometry, are considered to have faces when lateral sides are flat, that is, planar. 

Factor (Noun) 
The noun Factor is a value that is multiplied with another Factor (or factors) to result in a product. That product of two or more factors is the result of the operation of multiplication. 

Factor (Verb) 
The verb Factor is the act of dividing some entity into components or pieces that, when multiplied together, produce the given entity. We "break apart" some real value or quantity into its multiplicative factors when we Factor. 

Factor Tree 
A Factor Tree is a written mechanism to see the factors or prime factors of some value (usually an integer, but not necessarily). 

Factorial 
A Factorial results from the multiplication of successive positive integers. The term Factorial is either a function or a number, depending on its specific use. 

Fibonacci Numbers 
This set of numbers itself grows without bound, but the ratio of successive terms in the series converges to the golden ratio. 

Finite 
The common meaning of Finite and its meaning to mathematicians are not quite the same. In everyday language, Finite means countable within a reasonable time. To math people, Finite means not infinite; it means, simply, having a bound. 

First Derivative 
The First Derivative of a typical function, say, y = f(x), is the slope of the line tangent to a point on the graph of the original function f(x). 

First Order Differential Equation 
This type of equation includes first derivatives and employs algebra to treat those derivative functions as variables. 

First Order Polynomial 
This type of equation has no variables raised to integer powers greater than one. 

First Quartile 
In certain sets of data it is appropriate to divide the values into fourths by frequency of occurrence. The First Quartile is the 25th percentile, or the highend value of the lowend quarter of data values. 

First Quintile 
In certain sets of data it is appropriate to divide the values into fifths by frequency of occurrence. The First Quintile is the 20th percentile, or the highend value of the lowest 20 percent (fifth) of data values. 

Fixed 
Fixed terms or values are constant, never changing value. 

Foci 
Certain points in conic sections (and other geometric entities) are termed Foci, the plural of focus. They are important to the mathematical mechanics of the functions. 

Focus 
A specific point in a conic section (or other geometric entity) is termed a Focus, the singular form of the word foci. They are important to the mathematical mechanics of the functions. 

Foil (Fiol) 
A mnemonic for remembering "firstoutsideinsidelast" for multiplication of two binomials. It is equivalent the FIOL, as we take the sum of products. 

Formula 
A recipe or algorithm for calculation, evaluation, simplification, or just about anything we do in mathematics can be called a Formula. 

Fourth Quintile 
When data is appropriately characterized by percentiles, the Fourth Quintile is the 80th percentile, with only 20 percent of the data values greater than this; it is the bottom of the highest fifth. 

Fractal 
Certain shapes maintain their shape through all permutations of multiplication, growth, dilation, division, contraction, or shrinkage. Such shapes are Fractals. 

Fraction 
Fractions are many, many things. But always, without fail, fractions are the result of dividing the top value (numerator) by the bottom value (denominator). 

Fractional Exponents 
Real values can be raised to powers that are integers or fractions. Fractional Exponents can be thought of as having a denominator that is the root of the value being raised to the power, with a numerator akin to an integer power. 

Frequency 
How often (or frequently) does something occur? That is its Frequency. The Frequency of a waveform is inversely proportional to its wavelength. 

Frustum 
Slice a pyramid (or cone) parallel to its base, remove the top. What remains under the "missing top" is the Frustum. 

Function 
Function takes on several meanings in the language of mathematics. A typical connotation is a relation between variables where for any input (an independent variable or element from the domain) we have a unique output (element in the range, or dependent variable result). 

Fundamental Theorem of Algebra 
Singlevariable polynomials with complex coefficients have at least one complex root. The field of complex numbers is closed. 

Fundamental Theorem of Arithmetic 
A theorem that all integers can be written as the product of prime numbers is often called the Fundamental Theorem of Arithmetic. 
