absolute value
the distance of a number on the number line from zero
Because it is a measurement, distance is always positive. So the absolute value of a number is always positive. We write the absolute value of a number a as ½a½.
acute angle
an angle with a measure between 0 and 90 degrees
acute triangle
a triangle that has three acute angles
addend
in addition, any one of the numbers added
The addends are the numbers that make up the addition problem. The sum or the total is the answer to the addition problem.
addition
the process of finding the total or sum of two numbers; the arithmetic operation that combines amounts; the process of moving to the right on the number line
We use the plus sign (+) to show addition in a problem. An addition problem can be written either vertically or horizontally.
addition property of zero
Adding zero to a number does not change the number.
Stated formally: For any real number a, a + 0 = a and 0 + a = a.
adjacent angles
angles that have the same vertex, have a side in common, and do not overlap
adjacent sides
sides of a polygon that have a common endpoint
algorithm
a set of rules for performing a procedure; a special method to solve a certain kind of problem
For example, one algorithm for computing the area of a rectangle is to measure the length and width of the rectangle [using the same unit of measurement] and then to multiply the length times the width.
alternate exterior angles
two angles that are on opposite sides of the transversal and that lie outside the parallel lines
alternate interior angles
two angles that are on opposite sides of the transversal and that lie between the parallel lines
altogether
every one of something; in all
For example, Claire has six pennies in her left hand and four pennies in her right hand. If I ask, "How many pennies does she have altogether?" the altogether tells me to add to get the answer.
amount
the sum or total of something; the quantity or value of something
Sum and total are words that also mean the answer to an addition problem; amount can be a more general word meaning how much of something. For example, I can say, "Mix the flour with a small amount of water." Here I am leaving it up to you how much is small.
angle
the shape made by two rays meeting at a common point (called a vertex) or by two plane surfaces meeting along a line; the space between two such rays or plane surfaces
area
the size of a surface, given in square units
You can compute the area of a plane (2-dimensional) figure or the area of a surface on a solid (3-dimensional) figure; however, when you refer to the area of all the surfaces on a solid, you call it surface area.
associative property of addition/associative property of multiplication
Grouping does not affect the sum or product of three numbers. When I add three numbers or multiply three numbers, the order in which I do the addition or multiplication doesn't matter.
Formally stated: For real numbers a, b, and c, (a + b) + c = a + (b + c) and (ab)c = a(bc).
at
for the price of
For example, "Ben bought three pens at $1.19 each."
The symbol @ is used for at, both in math problems and in Internet addresses.
attribute
a characteristic that distinguishes an object from other objects
For example, the geometric shapes that we call quadrilaterals share the attribute of having four sides. Rectangles, rhombuses, squares, trapezoids and parallelograms all have this attribute, but a triangle (which has only three sides) does not have this attribute. Attributes are the qualities that allow us to group similar objects or numbers together and to decide when an object or number doesn't fit in a group.
average
the arithmetic mean of a group of numbers, computed by adding the list of numbers and then dividing by the number of items in the list; a common measure of central tendency
To find the average of 2, 4, 6, and 24, first add them up. 2 + 4 + 6 + 24 = 36. Then count up the number of items on your list (4), and divide that into your total. (36 divided by 4 = 9). Note that the average does not have to be one of the numbers in your original list.
axes
the plural of the word axis; in the rectangular coordinate system, the two number lines that intersect to form right angles
In the above rectangular coordinate system, the two axes are labeled x and y.
balancing a checkbook
determining if the checking account balance is accurate, done by comparing the monthly bank statement to the figures in the checkbook register and the receipts from various transactions
bar graph
a graph that displays data as vertical or horizontal parallel bars
base
the number that is raised to a power
In the expression 4³, 4 is the base, the number we are cubing.
base of a triangle
the side to which the line segment for the height of the triangle is drawn
base ten number system
also called the decimal number system; the number system we use in everyday life, which uses ten basic symbols {0,1,2,3,4,5,6,7,8, and 9} and makes up all other numbers using combinations of these ten basic symbols
bases of a trapezoid
the two parallel sides of a trapezoid
basic percent equation
"Percent times base equals amount"; also stated "Percent times the whole equals the part."
benchmark
a number that can be used to estimate the size of other numbers; a mark representing a known number, used as a reference point
For example, on some amusement park rides, only children over a certain height are allowed. The person running that ride might make a black line on the gate to the ride at the minimum allowable height. He uses the line as a benchmark to decide if a child is tall enough to go on his ride.
bisect
to divide a line segment into two equal parts; to divide a shape into two congruent parts
If line segment AB equals line segment BC, then the dotted line bisects line segment AC. If rectangle DEGH is congruent to rectangle EFHJ, then the dotted line segment EH bisects rectangle DFGJ.
borrow
in subtraction, to regroup from a larger place value to a smaller pace value
British thermal unit (BTU)
a unit of heat; the quantity of heat needed to raise one pound of water one degree Fahrenheit
broken-line graph
a graph that represents data by the position of the lines and shows trends and comparisons
