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EnchantedLearning.com Math Dictionary

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E is for ...

e e e is a transcendental number that is equal to approximately 2.71828182845904523536028747135266249... e is an irrational, non-repeating decimal and is the base of the natural logarithm. The symbol e honors the Swiss mathematician Euler (e is sometimes called Euler's number).

eight Eight is the number between seven and nine. Spiders have eight legs. Stop signs have eight sides. An eight-sided figure is called an octagon.

18 eighteen Eighteen is the number between seventeen and nineteen. An eighteen-sided polygon is called an octadecagon.

80 eighty Eighty is the number between seventy-nine and eighty-one.

11 ***** ****** eleven Eleven is the number between ten and twelve. Eleven is ten plus one. An eleven-sided figure is called a hendecagon or an undecagon.

ellipse An ellipse looks like a flattened circle. It consists of all the points in a plane that satisfy the following: a+b=(twice the length of the semi-major axis), where a is the distance from one focus to the point on the ellipse, and b is the distance from the other focus to the same point on the ellipse.

{ } empty set The empty set (also called the null set) is the set that has no elements.

enneadecagon An enneadecagon is a nineteen-sided polygon.

= equal When two things are equal they are exactly the same in number, quality, or amount.

1+1=2 3-x=2 equation An equation is a mathematical statement that contains an equal sign, like ax + b = c.

equator The equator is an imaginary circle around the Earth or any orb, halfway between the North and South Poles.

equilateral triangle The sides of an equilateral triangle are all the same length and all the interior angles are 60 degrees.

Escher, M.C. Maurits Cornelis Escher (June 17, 1898-March 27, 1972) was a Dutch artist known for his woodcuts of interlocking geometric patterns and impossible constructions.

0, 2, 4, 6, 8, 10, ... even number An even number is divisible by two.

! exclamation point In mathematics, the exclamation point means factorial. The factorial of a number is equal to the number times all the positive whole numbers less than it. For example, 5!= 5x4x3x2x1=120

xn exponent An exponent is a power that a number is raised to. For example, in 23, the exponent is 3.

exponential notation Exponential notation (also called scientific notation) is a short-hand way of expressing very small or very large numbers; this system avoids using a lot of zeros by using powers (exponents). In scientific notation, there is a number between 1 and 10 multiplied by a power of ten. For example, the number 250 written in scientific notation is 2.5 x 102. For another example, the number 0.000052 written in scientific notation is 5.2 x 10-5.

expression An algebraic expression consists of one or more variables, constants, and operations, like 3x-4. Each part of an expression that is added or subtracted is called a term For example, the expression 4x2-2x+7 has three terms.

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EnchantedLearning.com Math Dictionary

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Counting

Addition

Subtraction

Multiplication

Division

Number Line

Fractions

Decimals

Graphs

Measurement

Rounding

Click on an underlined word for more information on that subject. If the math term you are looking for is not in the dictionary, please e-mail us.

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