Glossary Entries
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 | ZData | Information collected and used to analyze a particular concept or situation.
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Day | A unit used to measure time; 1 day = 24 hours.
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Decagon | A decagon is a ten-sided shape (polygon).
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Deciles | The 10th, 20th, 30th, ...90th percentile points (See definition for Percentile.) |
Decimal Fraction | A fraction using a decimal point to represent the denominator of 10 or a power of 10. |
Decimal Number | A fractional number that is written using base ten notation. A mixed decimal number has a whole number part as well. Example: 0.28 is a decimal number and 3.9 is a mixed decimal number.
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Decimal Point | A period or dot separating the ones place from the tenths place in decimal numbers or dollars from cents in money. It looks like a period. Example: For "2.13" the decimal point is after the two. |
Decimeter | One-tenth of a meter, a decimeter is approximately the distance from one’s wrist to the end of one’s thumb.
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Decompose | To break a number into smaller units to simplify computation. Example: 15 = 10 + 5.
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Decomposition | The process of breaking a number into smaller units to simplify computation.
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Decrease | To take away or become smaller.
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Deductive Reasoning | Using logic to arrive at a conclusion from a given premise.
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Degree | A unit used to measure angles. There are 360 degrees in a circle. |
Degree of a Monomial | The sum of the exponents on the variables contained in a term. Example: The degree of 3x3y4 is 7. |
Degree of a Polynomial | The largest degree among all its terms. |
Denominator | The bottom number of a fraction. For 1/2 the denominator is 2. |
Density | The amount of mass per unit of volume. |
Dependent Events | Two events in which the outcome of the first event affects the outcome of the second event (e.g., drawing two marbles from a bag of red, green, and blue marbles without replacement). |
Diameter | The distance from one side of the circle to the other side when the line (chord) is drawn through the center point. It is a value that is two times the length of the radius. |
Difference | The answer in a subtraction problem. One value is subtracted form another and the result is the difference. Technically, the subtrahend is subtracted from the minuend. |
Digit | Any one of the ten numerical symbols:0, 1, 2, 3, 4, 5, 6, 7, 8, or 9. |
Digital Clock | A clock on which the time is displayed numerically. Example: The time is displayed as 12:22. It is twenty-two minutes after twelve o’clock. |
Dilation | A transformation that stretches or shrinks a function or graph both horizontally and vertically by the same scale factor. |
Dime | A coin with a value of 10 cents or one tenth of a dollar. |
Dimensional Analysis | A method of manipulating unit measures algebraically to determine the proper units for a quantity computed algebraically. For example, velocity has units of the form length over time (e.g., meters per second [ m/sec ]), and acceleration has units of velocity over time; so it follows that acceleration has units ( m/sec)/sec = m/(sec2). |
Dimensions | Measurements of a figure. Examples include the length, width, and height of a prism. |
Direct Measurement | A process of obtaining the measurement of some entity by reading a measuring tool, such as a ruler for length, a scale for weight, or a protractor for angle size. |
Discount | A reduction made from the gross amount or value of something; a reduction made from the regular or list price. |
Discover | To make note of possible patterns and generalizations that result from investigation/exploration. |
Dispersion | The scattering of the values of a frequency distribution (of data) from an average. |
Distance | The length of the line segment joining two points. |
Distributive Property | A property of real numbers that states that the product of the sum or difference of two numbers is the same as the sum or difference of their products. Example: 6x(2+3)=(6x2)+(6x3) -- Multiplication over addition. Example 2: 5 x 23 = 5 x (20 + 3) = 5 x 20 + 5 x 3 = 100 + 15 = 115. |
Dividend | A number that is divided by another number. |
Divisible | If a number has a whole number answer when divided by a second number, the first number is divisible by the second number; x is divisible by y if and only if x = qy where y is a whole number. |
Division | A mathematical operation involving two numbers that tells how many groups there are or how many are in each group. The symbol for division is ÷ or /. |
Divisor | The number by which the dividend is divided. |
Dollar | Currency that is worth 100 cents. You will see the symbol "$" when working with dollars. |
Domain | The set of values for which a function is defined. |
Double | To make twice as great or as many; to increase by adding an equal amount; to amount to twice the number. |
Double-Bar Graph | A graph that uses pairs of bars to compare and show the relationship between data. |
Double-Line Graph | A graph that uses pairs of lines that show change over time to represent and compare data. |
Useful Reference Materials
Wikipedia:https://en.wikipedia.org/wiki/Fraction_%28mathematics%29
Encyclopædia Britannica:
http://www.britannica.com/topic/fraction
University of Delaware:
https://sites.google.com/a/udel.edu/fractions/