Math Glossary Letter D
d=rt
Distance formula
day
A unit of time equal to 24 hours
debt
money owed by one party to another party
decade
A unit of time equal to 24 hours
decagon
10 sided polygon or 10-gon
decay
Reduction in size from decomposition
deciliter
A unit of liquid measurement
decimal
Number in the form a/b where the result is not a whole number
decimal degrees
express latitude and longitude geographic coordinates as decimal fractions
declining balance depreciation
depreciation method using a ratio of salvage to asset value as a factor
decompose fraction
break apart a fraction where the numerators equal 1
deficient numbers
A number (n) with the sum of proper factors less than n
degree
A unit of angle measurement, or a unit of temperature measurement
degrees of freedom
number of values in the final calculation of a statistic that are free to vary
delta
A measure of change
demoivres theorem
A formula useful for finding powers and roots of complex numbers

z = rcis(θ), then zn = rncis(nθ)
denomination
A currency unit
denominator
The bottom portion of a fraction. For a/b, b is the denominator
density
The compatness measure of an object
dependent variable
A variable reliant on another variable
depreciation
The reduction in value of an asset over time
derangement
permutation with no fixed points

!n
derivative
rate at which the value y of the function changes with respect to the change of the variable x
descartes rule
determine the number of real zeros of a polynomial function
determinant
value computed from a square matrix

det(A) or |A|
dewey decimal system
proprietary library classification system
diagonal
line segment that goes from one corner to another, but is not an edge
diagonal of a square
line segment that goes from one corner of a square to another, but is not an edge
diagonals of a polygon
line segment that goes from one corner of a polygon to another, but is not an edge
diameter
distance from two endpoints of a circle through the center
diameter of a circle
distance from two endpoints of a circle through the center
diameter of a cylinder
distance from two endpoints of a cylinder through the center
diametrically opposed
Two points on a circle or sphere at opposite ends of the diameter.
dice
objects used in games of chance wih 6 sides
dice's coefficient
statistic used for comparing the similarity of two samples

|A ∩ B|/(|A| + |B|)
difference of proportion
hypothesis test to determine whether the hypothesized difference between population proportions differs significantly from the observed sample difference
difference of squares
Binomial factoring formula

a2 - b2 = (a + b)(a - b)
digit
Any of the numbers (0, 1, 2, 3, 4, 5, 6, 7, 8, 9) used to construct a number
digit problems
math problems involving variables for each place value, h for hundreds, t for tens, and o for ones as an example
digit sum
Adding the digits of a number and repeating the process of the sum until the final sum is less than 10
digraph
a combination of two letters representing one sound
dime
currency unit worth 10 cents
diophantine
equation in which only integer solutions are allowed
direct current
Undirectional flow of an electric charge
directrix
line in a parabola not through the focus
discrete math
Deals with math structures which is not continuous, rather discrete
disjoint sets
Sets with no common elements
displacement
Movement of an object from it's current position
distance
interval between two points in time

d = rt
distance catch up
word problems involving a staggered start between 2 people or objects to see when they meet
distance rate and time
formula relating distance, rate, and time

d = rt
distribution
value range for a variable
Distributive Property
Property stating you can multiply a sum by multiplying each addend separately and then add the products

a(b + c) = ab + ac
dividend discount model
A formula used to value a stock based on the present value of dividends

P = D/(i - k) where i is the interest rate and k is the growth rate of dividends
dividing
separate a number into parts
divisibility
Determine factors (whole numbers) for a given number
division
separate a number into parts
division equality
f you divide one side of an equation by a number, you also must divide the other side by the same number so that your equation stays the same
Division Property of Inequality
f you divide one side of an inequality by a number, you also must divide the other side by the same number so that your inequality stays the same
dollar
Currency unit
dollar weighted interest method
Evaluating a fund's interest based on the amount invested
domain
Set of all possible input values which makes the output value of a function valid
dot product
Multiplying two vectors
double
Multiply by 2
double declining balance depreciation
depreciation method using a ratio of salvage to asset value as a factor. The asset loses value at twice the rate of the straight line depreciation method
double factorial
Factorial method subtracting 2 from each successive number, instead of 1 like a standard factorial

n!!
dozen
Quanity of 12
drawing from a container
Probability method of selecting objects from a container and computing the probability
duplication and mediation
Algorithm to compute the product of two numbers, using even sub-products