Terms  Definitions 

acute angle 
an angle that has a measure greater than 0* and less than 90*

acute triangle 
a triangle in which each of the three angles measures less than 90*

addend 
a number that is added in an addition problem

addition sequence 
an ordered list of numbers in which the same number is added to the previous term to get the following term

algebraic addition 
the addition of the opposite of a number; used to replace subtraction

a.m. 
before noon (ante meridiem)

angle 
an opening between two intersecting lines, rays, or segments

Arabic numerals 
the digits (0,1,2,3,4,5,6,7,8, and 9) used in combination with place value to express numbers. For example, 475 is an Arabic numeral.

area 
the number of square units of a given size that cover the surface of a figure

average 
the amount found by dividing the sum of a set of numbers by the number of numbers in the set, also known as arithmetic average or mean

base 
in a triangle or parallelogram, the side from which the height of the triangle or parallelogram is measured

Celsius scale 
one of the scales used on a thermometer to measure temperature. on this scale, water boils at 100*C and freezes at 0*C. normal body temperature is 37*C

century 
one hundred years

chance 
the likelihood that something will happen, expressed as a percentage

circle 
a round graph in which every point on the graph is the same distance from a center point

circumference 
the distance around a circle, also known as the perimeter of a circle

common number 
a number shared by two or more sets, as in common factor, common multiple and common denominator

compare 
to determine whether one number or expression is greater than, less than, or equal to another number or expression

compass 
a tool that aids in the drawing of circles, as well as in other geometric applications

composite 
a number that has more than two factors

cone 
a threedimensional solid with a circular base and a single vertex

congruent 
a set of figures that have the same shape and size. also, angles or line segments that have the same measure

coordinate plane 
a graph of two perpendicular number lines that have scale marks extended to form a grid on which to plot points

coordinates 
a paired set of numbers like (3, 2) that indicates the location of a point on a coordinate plane. the first number shows the horizontal direction and distance from the origin (on the xaxis); the second number shows the vertical direction and distance from the origin (on the yaxis)

counting numbers 
the numbers in this sequence: 1,2,3,4,5,....

cross products 
the result of taking a pair of fractions and multiplying the numerator of the first fraction by the denominator of the second fraction and vice versa

cube 
a threedimensional solid with six square faces. adjacent faces are perpendicular, and opposite faces are parallel

cylinder 
a threedimensional solid with two circular bases, that are opposite and parallel to each other

decade 
ten years

decimal places 
all of the place values to the right of the decimal point

decimal point 
a period used to separate the ones' place from the tenths' place

degree (*) 
the unit used to measure angles. also, the symbol used to denote unit divisions on a temperature scale

denominator 
the bottom number of a fraction, designating the number of equal parts in a whole number

diameter 
the distance across a circle throught the center of the circle

difference 
the result of subtraction

digit 
any one of the following ten numerical symbols: 0,1,2,3,4,5,6,7,8,9

dividend 
the number that is divided in a division problem

divisible 
the ability to be divided without a remainer; for example 6 is divisible by 1,2,3, and 6

divisor 
the number by which another number is divided

edge 
a line at which two faces of a solid come together

endpoints 
the points at which a line segment ends

equals sign (=) 
a symbol that indicated that two numbers or expressions are equivalent

equilateral triangle 
a triangle in which all three sides and all three angles are equal in measure

equivalent 
expressions that have the same value; for example, 2/4 is equivalent to 1/2, or 2/4 = 1/2

estimate 
to roughly determine a size or value; to calculate approzimately using rounded numbers

even numbers 
those numbers that can be divided by 2 without a remainer. the digit in the ones' place of an even number is 0,2,4,6, or 8

experimental probability 
the probability of an event occurring as determined by data collection

exponent 
a number that indicates repeated multiplication of the base. for example, in 5 to the 2nd, 2 is the exponent and 5 is the base, and this means 5 x 5, or 25

face 
a flat surface of a solid

fact families 
sets of three numbers which can be formed into two addition facts and two subtraction facts, or two muliplication facts and two division facts

factor 
a number being multiplied. also, a whole number which divides another whole number without a remainer

Fahrenheit scale 
one of the scales, used on a thermometer to measure temperature. on this scale, water boils at 212*F and freezes at 32*F. normal body temperature is 98.6*F

fraction 
a common fraction is part of a whole, expressed as a numerator over a denominator

geometry 
the study of shapes

graph 
a diagram such as a bar graph, a circle graph (pie chart), or a line graph that displays quantitative information

greater than/less than sign (< >) 
a symbol placed between two numbers or expressions to indicate which is greater or which is less

greatest common factor (GCF) 
the largest whole number that is a factor of all members of a given set of whole numbers

height 
in a triangle or parallelogram, the perpendicular distance from the base to the opposite vertex of a trianle or from the base to the parallel side of a parallelogram

hexagon 
any sixsided polygon

histogram 
a special type of bar graph that displays data in equivalent intervals with no space between the bars

horizontal 
parallel with the horizon; perpendicular to vertical

hundredths' place 
the place value two places to the right of the decimal point. each hundredth equals 1/100

improper fraction 
a fraction in which the numerator is equal to or greater than the denominator; a fraction that is equal to or greater than one

integers 
the set of numbers that includes all the counting numbers, their opposites, and zero

intersecting lines 
lines that cross; lines which share a common point

irrational number 
a number that cannot be expressed as a fraction. examples are ∏ and √2

isosceles triangle 
a triangle in which at least two of the three sides and angles are equal in measure

length 
a longer side of a rectangle

least common multiple (LCM) 
the smallest number that is a multiple of a given set of whole numbers

line 
a continuous string of points extending in two opposite directions without end

line of symmetry 
a line that divides a figure into two mirror images

mass 
the amount of matter in an object

mean 
the average of a set of numbers

median 
in a set of numbers arranged in order from least to greatest, the middle number, or the average of the two middle numbers

metric system 
an international system of measure based on multiples of ten using units such as meters, liters, and grams

mixed numbers 
an expression made up of a whole number and a fraction, such as 2 3/4

mode 
the most frequently occurring number or numbers in a set of numbers

mulitple 
a number found by multiplying a given number by a whole number greater than zero; for example, the multiples of 5 are 5,10,15,20,....

multiplication sequence 
an ordered list of numbers in which the same number is multiplied by the previous term to get the following term

negative 
a number less than zero; the opposite of positive

noon 
midday; 12:00 p.m.

number line 
a line with evenly spaced marks on which a number is associated with each mark

numeral 
a written symbol for a number

numerator 
the top number of a fraction, designating the number of parts being used

oblique 
slanted, sloped, or inclined lines; neither horizontal nor vertical; neither parallel nor perpendicular

obtuse angle 
an angle that has a measure greater than 90* but less than 180*

obtuse triangle 
a triangle in which one angle measures greater than 90*

octagon 
any eightsided polygon

odd numbers 
those numbers that have a remainder of 1 when divided by 2. the digit in the ones' place of an odd number is 1,3,5,7, or 9

operation of arithmetic 
mathematical processes performed according to specific rules. these processes are addition, subtraction, multiplication, and division

opposites 
those numbers that can be written with the same digits but with opposite signs. for example, the opposite of 5 is 5. the sum of a number and its opposite is zero

origin 
the point (0,0) on a cordinate plane at which the xaxis and yaxis intersect

parallel 
lines, rays, or segments that remain the same distance apart and do not intersect

parallelogram 
a quadrilateral that has two pairs of parallel sides

pentagon 
a fivesided polygon

percent 
a fraction with the denominator 100 expressed with a percent sign, %. for example, 99% = 99/100

perfect square 
a number that has as its square root a whole number. examples of perfect squares are 1, 4, and 9

perimeter 
the distance around a shape

perpendicular 
lines, rays, or segments that intersect to form right angles

pi (∏) 
the Greek letter that stands for the number of diamteters in a circulference (approximately equal to 3.14)

place value 
the value of a digit determined by its position within a numeral

p.m. 
after noon (post meridiem)

polygon 
any straightsided closed plane figure

polyhedron 
a solid figure on which every face is a polygon

positive 
a number grater than zero; the opposite of negative

prime 
a counting number that has exactly two factors, the number 1 and itself

prime factorization 
the breakdown of a counting number by writing it as a product of its prime factors

prism 
a threedimensional solid that has two congruent, parallel polygons as its base

probability 
the likelihood that something will happen expressed as a ratio

product 
the result of multiplying

proper fraction 
a fraction in which the numerator is less than the denominator

proportion 
a true statement that dmonstrates two rations are equivalent

protractor 
a tool that is used to measure and draw angles

pyramid 
a threedimensional solid with a polygon as its base and triangular sides that meet at a vertex

quadrilateral 
any foursided polygon

quotient 
the result of division

radius 
the distance from the center of a circle. the plural of radius is radii

range 
the difference between the greatest and the least in a set of numbers

ratio 
an expression of the relationship between two numbers using a colon, a fraction, or words, such as 3:2, 3/2, or 3 to 2

ray 
the portion of a line that begins at one point and continues without end

reciprocal 
the fraction resulting from inverting a given fraction (reversing the numerator and denominator). the product of a fraction and its reciprocal is one

rectangle 
a foursided polygon that has four right angles

rectangular prism 
a prism with rectangles as bases

rectangular solid 
a threedimensional solid where all six faces are rectangles. opposite faces are parallel and adjacent faces are perpendicular

reduce 
to divide a fraction by another fraction equal to 1 in order to form an equivalent fraction in which both the numerator and denominator have lesser values. for example, 2/4 reduces to 1/2

reflection 
a transformation performed by reflecting a figure as in a mirror or flipping a figure over a certain line

regular polygon 
a polygon in which all sides and angles are equal in measure

remainder 
in subtraction, the difference; in division, any number that is left over after dividing integers

rhombus 
a parallelogram that has sides of equal length

right angle 
a square angle, often marked with a square, that has a measure of 90*

right triangle 
a triangle in which one angle measures 90*

Roman numerals 
an ancient form of numbering that does not use place value; for example II is a Roman numeral equivalent to the Arabic numeral 2

rotaion 
a transformation performed by turning a figure about a certain point

rounding 
finding another number that is near the number given; for example, 587 rounds to 600

sales tax 
the tax charged on the sale of an item based upon the selling price

scale 
a system of marks at regular intervals used for measurement. also, an instrument that displays such marks

scalene triangle 
a triangle in which all three sides and all three angles are not equal in measure

segment 
a part of a line that has two endpoints

sequence 
an ordered list of numbers that follows a certain rule

side 
a line segment of a polygon; the number of sides indicates the type of polygon

similar 
a set of figures or angles that are the same shape but not necessarily the same size

solid 
a geometric shape that occupies space

sphere 
a smooth geometric solid that is shaped like a ball

square 
a rectangle in which all sides are the same length

square root 
a number that, when multiplied by itself, equals the given number. the square root of 49 is 7 because 7 ∙ 7 = 49. the principal of the positive square root of a number is indicated by this symbol, √

straight angle 
an angle that forms a straight line and has a measure of 180*

sum 
the result of addition

surface area 
the total area of all of the surfaces of a geometric solid

survey 
a method of collecting data about a particular population

tenths' place 
the place value one place to the right of the decimal point. each tenth equals 1/10

theoretical probability 
the probability of an event occurring as determined by analysis rather than by experimentation

thousandths' place 
the place value three places to the right of the decimal point. each thousandth equals 1/1000

transformation 
any of the three forms of movement (rotation, reflection, and translation) made to reposition a figure

translation 
a transformation performed by sliding a figure in one direction without turning the figure

trapezium 
a quadrilateral in which no sides are parallel

trapezoid 
a quadrilateral in which one pair of sides are parallel

triangle 
a polygon that has three sides and three angles, the sum of which measure 180*

unit multiplier 
a fraction equal to one, written with two different but equivalent units of measure; for example, 1 ft/12 in is a unit multiplier

U.S.Customary System 
a U.S. system of measure using units such as fee, gallons and pounds

vertex 
the point at which two sides of a polygon or three or more edges of a polyhedron intersect. the plural of vertex is vertices. note that a cone also has a vertex. this vertex is not made from the intersection of edges, but rather the intersection of the lines that would make up the nonbase surface of the cone

vertical 
upright; perpendicular to horizontal

volume 
the amount of space a given shape occupies

whole numbers 
all the counting numbers and zero, as in the sequence: 0,1,2,3,4,....

width 
a shorter side of a rectangle

xaxis 
the horizontal number line of the coordinate plane

yaxis 
the vertical number line of the coordinate plane

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