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+,   Math Dictionary 
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MOM 2002 palindrome A palindrome is a word, phrase or number that reads the same forwards or backwards. A palindromic number is a number that reads the same forwards or backwards, like 2002. Some other palindromes are: the name Bob, the number 101, and the phrase, "Madam, I'm Adam." 
parabola A parabola (a type of conic section) is a curve that is a set of points P such that the distance from a line (the directrix) to P is equal to the distance from P to the focus F. Parabolas have an eccentricity of 1. 
parallel Parallel lines extend in the same direction, are always the same distance apart, and never intersect (meet). 
parallelogram A parallelogram is a foursided figure (a quadrilateral) whose opposite sides are parallel. 
Pascal's triangle Pascal's triangle is a triangular pattern of numbers devised in 1653 by the French mathematician, physicist, and philosopher Blaise Pascal (June 19, 1623  Aug. 19, 1662). The numbers in each row are derived by adding pairs of numbers in the row above it. The number one is tacked onto the beginning and end of each row. The first few rows of Pascal's triangle are shown above. The rows represent the binomial coefficients in a triangular format. Note that the row with the numbers [1 2 1] represents the coefficients of (x+y)^{2}. The nth row represents the coefficients of (x+y)^{n}. 
pattern A pattern is something that is repeated, like a design or a series of numbers. 
penny A penny is a coin worth one cent. 
pentadecagon A fifteensided polygon is called a pentadecagon. 
pentagon A pentagon is a fivesided polygon. 
% percent Percent mean "per hundred." The sign for percent is %. 100% means all, 50% means half or 50 out of 100, 25% means one quarter or 25 out of 100, 10% means one tenth or 10 out of 100, and 0% means none or 0 out of 100. To convert a percentage to decimal notation, divide the percentage by 100; for example, 50% = 0.5 and 10% = 0.1. To convert a decimal to a percent, multiply the number by 100; for example, .25 = 25%. 
perfect number A perfect number is an integer for which the sum of its proper factors (divisors) is equal to the number itself. For example, 6 is a perfect number because the proper divisors of 6 are 1, 2, and 3 which add up to 6. Compare with abundant number, deficient number. 
perimeter Perimeter is the distance around the edges of a figure. The perimeter of a square with side length a is P = a+a+a+a = 4 times a. The perimeter of a circle is P = 2πr. The perimeter of a regular polygon is P = ns (where n is the number of sides and s is the side length). 
perpendicular When two lines are perpendicular, they are at right angles (90 degrees). A line can also be perpendicular to a plane (if the line goes through the plane at a 90 degree angle). 
pi Pi is the ratio of the circumference of a circle to the diameter of a circle. For any circle, you can divide the circle's circumference (the distance around the circle) by the diameter (the distance across the circle through the center) and you will always get exactly the same number (pi), no matter how big or how small the circle is. Pi is a number roughly equal to 3.14159265...  the digits of pi never end or repeat. The value of pi has been calculated up to the millions of digits. Pi is a transcendental number. 
pie chart A pie chart (also called a circle graph) is a diagram that is useful for displaying information about the percentages or parts of a whole. Pie charts were invented in 1801 by William Playfair (Sept 22, 1759  Feb 11, 1823). 
place value Place value is a positional system of notation in which the position of a number with respect to a point determines its value. In the decimal (base ten) system, the value of the digits is based on the number ten. 
plane A plane is a flat (2dimensional) surface that extends to infinity in all directions. A plane has no thickness. 
Platonic solid Shapes that are also called regular polyhedra. The five regular polyhedra that were discovered by the ancient Greeks (and are named for the ancient Greek philosopher Plato). The Pythagoreans knew of the tetrahedron, the cube, and the dodecahedron; the mathematician Theaetetus added the octahedron and the icosahedron. Plato speculated that these five solids were the shapes of the fundamental components of the physical universe. 
plot A plot is a graph done in a coordinate system. Each point on the graph is plotted (marked on the graph in the coordinate system). 
+ plus sign A plus sign (+) means addition or indicates that a number is positive. 
. point A point is an exact location, a spot with no width or thickness. 
polygon A polygon is a manysided closed figure with straight edges. A regular polygon is a polygon whose sides are all the same length and whose interior angles are all the same (like an equilateral triangle or a square). 
polyhedron Polyhedra (the plural of polyhedron) are solids whose faces are polygons. 
A polynomial is a sum or difference of terms; each term is:
Degree of a Polynomial: The degree of a term within a polynomial is the sum of the exponents of variables that occur in that term (if there is no exponent written on a variable, such as in 3x, the exponent is one). The degree of a polynomial is the greatest degree of any term in the polynomial (for instance, for the polynomial 4x^{2} + 7xyz, the degree is 3 because of the last term).

polynomial equation A polynomial equation is an equation involving a polynomial. 
positive integer A positive integer is an integer (a whole number) greater than zero, like 1, 2, 3, 4, ... 
positive number A positive number is a number greater than zero. Numbers written without a sign are assumed to be positive. For example, 3 = +3. 
x^{n} power A power is the same as an exponent. For example, x to the second power is the same as x squared (x^{2}). A number x to the third power is the same as that number cubed (x^{3}). 
2,3,5,7,11,13,17... prime number A prime number is a positive number that has exactly two factors, 1 and itself. Alternatively, you can think of a prime number as a number greater than one that is not the product of smaller numbers. For example, 13 is a prime number because it can only be divided evenly by 1 and 13. For another example, 14 is not a prime number because it can be divided evenly by 1, 2, 7, and 14. The number one is not a prime number because it has only one factor, 1 itself. 
protractor A protractor is a device that measures angles. 
Ptolemy Claudius Ptolemaeus or Ptolemy (about 87150) was a Greek astronomer and mathematician who wrote about his belief that all celestial bodies revolved around the Earth. His writings influenced people's ideas about the universe for over a thousand years, until the Copernican System (with a heliocentric solar system) was accepted. 
pyramid A pyramid is a shape that has a flat polygonal base and triangular sides that meet at a point on the top. The pyramids in Egypt are huge buildings built by ancient Egyptians. 
Pythagoras Pythagoras of Samos (569475 BC) was a Greek philosopher, mathematician, and astronomer who founded a philosophical and religious school, the Pythagorean school in Croton, Italy. Pythagoras believed that the Earth was a sphere at the center of the Universe. He correctly realized that the morning star and the evening star were the same object, the planet Venus. Pythagoras (or the Pythagoreans) made a number of fundamental mathematical discoveries: that for a right triangle, the sum of the squares of the two shorter sides is equal to the square of the hypotenuse (known as the Pythagorean theorem); that the sum of the angles of a triangle is equal to two right angles; and that irrational numbers exist. A 142 km wide lunar crater was named for Pythagoras (Latitude 63.5°, Longitude 63.0°). 
Pythagorean theorem The Pythagorean theorem states that for a right triangle, the sum of the squares of the two shorter sides is equal to the square of the hypotenuse: a^{2} + b^{2} = h^{2}. 
+,   Math Dictionary 
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Counting  Addition  Subtraction  Multiplication  Division 
Number Line  Fractions  Decimals  Graphs  Measurement  Rounding 
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