486A
acute angle An angle that measures less
than 90°.
addend A number that is added to another
number or numbers.
angle The figure formed by two rays that
meet at a common endpoint.
area The number of square units needed to
cover a flat surface.
associative (grouping) property Changing
the grouping of the addends (or factors)
does not change the sum (or product).
axis The horizontal or the vertical number
line of a graph.
C
capacity The amount, usually of liquid, that
a container can hold.
center A point from which every point on a
circle is the same distance.
centimeter (cm) A metric unit of length;
10 cm1 dm; 100 cm1m.
certain An event that cannot fail to occur, or
has a probability of 1.
circle A simple closed curve; all the points
on the circle are the same distance from
the center point.
circle graph A graph that uses sections of
a circle to represent data.
clustering To find addends that are nearly
alike in order to estimate their sum.
common factor A number that is a factor
of two or more products.
common multiple A number that is a
multiple of two or more numbers.
commutative (order) property Changing
the order of the addends (or factors) does
not change the sum (or product).
compatible numbers Two numbers, one of
which divides the other evenly.composite number A whole number
greater than 1 that has more than two
factors.
cone A solid figure that has one circular
base.
congruent figures Figures that have the
same size and shape.
cube A solid figure with six congruent
square faces.
customary system The measurement
system that uses inch, foot, yard, and mile;
cup, pint, quart, and gallon; and ounce and
pound.
cylinder A solid figure that has two
congruent circular bases.
D
data Facts or information.
decimal A number in base ten that is
written with a decimal point.
2.04 decimal
decimal point
decimeter (dm) A metric unit of length;
1 dm10 cm; 10 dm1 m.
degree () A unit used to measure angles.
degree Celsius (C) A unit for measuring
temperature. The freezing point of water is
0 C.
degree Fahrenheit (F) A unit for
measuring temperature. The freezing point
of water is 32F.
denominator The numeral below the bar in
a fraction; it names the total number of
equal parts.
diameter A line segment that passes
through the center of a circle and has both
endpoints on the circle.
difference The answer in subtraction.
digit Any one of the numerals 0, 1, 2, 3, 4,
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