Online Math Dictionary: A
Easy to understand math definitions for KAlgebra mathematics
Just scroll down or click on the word you want and I'll scroll down for you!


Absolute Value An absolute value is a number's distance from zero on the number line. Examples:  0  = 0  5  = 5  3  = 3 For more information on absolute values, check out my Absolute Value Review lesson. 

Acceleration Acceleration is the change in something's speed (velocity). When you are speeding up, you are accelerating. When you are slowing down, you are "accelerating"  well, that's what they'd say in a Physics class, but we say "decelerating." 

Acre An acre is a unit of measure used for measuring land in the United States. An acre is 43,560 square feet or 4,840 square yards. 


Addend In the example... 2 + 3 = 5 The 2 and the 3 are called addends. For more info, check out my Addition Lessons. 

Additive Identity In basic arithmetic, the additive identity is the number 0... Because you can ADD 0 to any number and that number keeps its identity (it stays the same). Example: 5 + 0 = 5 

Additive Inverse In basic arithmetic, an additive inverse is a number that you add to something to get 0 for the answer. Example: 5 + 5 = 0 The additive inverse of 5 is 5. 



Algebra In arithmetic, you always know what numbers you are working with... Like 8  2 = 6. In algebra, one or more of these numbers is unknown. They usually put an "x" in for the mystery number. Can you guess what x is here? 7 + x = 15. Easy! Of course, it gets a little harder than that... But, it's not bad. I've got a ton of algebra lessons on the site! 

Algorithm This is what they call it when Al Gore tries to dance. Ok, I know that was a really bad joke, but, typing out all these definitions is making me a bit loopy! An algorithm is a set of steps to complete a task. It may be the list of steps it takes to find the answer for a long division problem... Or it may be part of a computer program... It can even be the list of steps it takes for you to get ready to go to school in the morning. 





Alternating Sequence An alternating sequence is a list of numbers that goes positive, negative, positive, negative... or negative, positive,negative, positive. Example: 1, 2, 3, 4, 5, 6, 7, 8, ... For more info on sequences, check out my "What's a sequence?" lesson. 





Annual Annual means yearly or once a year. The term shows up in a lot of money problems in algebra. 

Annuity Mathematically speaking, an annuity is a series of equal payments made over a specified period of time. For example, if you put a certain amount of money each month into a savings account, that would be an annuity. Mortgages, monthly health insurance payments, and pension payments are other types of annuities. In the real world, an annuity is an investment (that you purchase) where you pay an annuity provider upfront to receive a certain amount of money each year or each month for a specified period. For example, when you retire, you can purchase a life annuity that pays out $1,000 each month for the rest of your life. 





Arithmetic Working with numbers, arithmetic is the process and study of addition, subtraction, multiplication and division. 

Associative Property of Addition The associative property of addition is a math rule that is always true. Here it is with letters: a + ( b + c ) = ( a + b ) + c Remember that you always do what's in the parenthesis ( ) first. This rule just says that, when you are doing addition, it doesn't matter which numbers you add first. You can add the a and b first OR you can add the b and c first and you'll get the same answer. Here it is with numbers so you can check this for yourself! 2 + ( 3 + 4 ) = ( 2 + 3 ) + 4 NOTE: This does not work with subtraction! 

Associative Property of Multiplication The associative property of multiplication is a math rule that is always true. Here it is with letters: a x ( b x c ) = ( a x b ) x c Remember that you always do what's in the parenthesis ( ) first. This rule just says that, when you are doing multiplication, it doesn't matter which numbers you multiply first. You can multiply the a and b first OR you can multiply the b and c first and you'll get the same answer. Here it is with numbers so you can check this for yourself! 2 x ( 3 x 4 ) = ( 2 x 3 ) x 4 NOTE: This does not work with division! 

Average This is the same thing as the "mean" of a group of numbers. It's weird to define "average" in words, but really easy to show what it is. Look at this list of numbers: 3, 6, 13, 4, 9... Add them up and we get 35... Now, divide by how many numbers there are. There are five numbers, so divide 35 by 5... We get 7 and that's the average of this list of numbers. Notice that some of the numbers are above 7 and some are below. 




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