abacus An abacus is an ancient device that is used for arithmetic calculations.	acute angle An acute angle is less than 90 degrees.	1+1=2 2+3=5 addition Addition is the adding of numbers to get their sum.	angle An angle is the amount of rotation it would take to put one intersecting line on top of another.	1+1=2 7-4=3 arithmetic Arithmetic is the study of addition, subtraction, multiplication, and division.
1,000,000,000 billion A billion is a thousand million. The Earth is billions of years old.	budget A budget is a written account of all income and expenses for a person, a family, an organization, or a government. People use budgets to figure out how much money they take in and plan how much they can spend and save.	chart A chart is a diagram, like a graph or a table, that shows the relationships between things.	circle All of the points on a circle are the same distance from the center.	cone A cone is a shape that has a point at one end and a circular opening at the other end. In mathematics, this shape is a half cone.
couple A couple refers to two people or two objects.	crescent A crescent is the shape of the moon a little before of after the time of the new moon.	cube A cube is a solid geometric figure with six square faces.	curve A curve is a wavy line.	cylinder A cylinder is a figure with a long round body .
denominator The denominator is the bottom number in a fraction.	diameter The diameter is the longest distance from one side of a circle (or a sphere) to the other.	diamond A diamond is a four-sided figure whose sides are all the same length. People play baseball on a diamond-shaped field.	dividend The dividend is the number that is divided (in long division). The dividend divided by the divisor is the quotient (plus a remainder).	division Division is an operation that divides a number into portions.
divisor The divisor is the number that the dividend is divided by (in long division). The dividend divided by the divisor is the quotient (plus a remainder).	dodecahedron A dodecahedron is a twelve-sided geometric solid whose faces are pentagons.	2 x double Double means twice or two times.	**** **** **** 12 dozen Dozen is another word for twelve.	eight Spiders have eight legs. Stop signs have eight sides.
18 ****** ****** ****** eighteen Eighteen is the number between seventeen and nineteen.	80 eighty Eighty is the number between seventy-nine and eighty-one.	11 ***** ****** eleven Eleven is ten plus one.	ellipse An ellipse is a flattened circle.	= equal When two things are equal they are exactly the same in number, quality, or amount.
equilateral triangle The sides of an equilateral triangle are all the same length.	0, 2, 4, 6, 8, 10, ... even number An even number is divisible by two.	Fahrenheit Fahrenheit is a measure of temperature that is abbreviated F. Water freezes at 32°F and boils at 212°F.	first The first person or thing comes before the others.	15 ***** ***** ***** fifteen Fifteen is the number after fourteen (14) and before sixteen (16).
50 ********** ********** ********** ********** ********** fifty Fifty is the number after forty nine (49) and before fifty one (51).	five People have five fingers on each hand.	40 ********** ********** ********** ********** forty Forty is the number after thirty nine (39) and before forty one (41).	four Squares have four sides. Cats and dogs have four legs.	14 ******* ******* fourteen Fourteen is the number after thirteen (13) and before fifteen (15).
fractal Fractals are patterns within patterns within patterns.	1/2 fraction A fraction is a part of a whole. Half of an apple is a fraction of an apple. The top number in a fraction is called the numerator; the bottom number in a fraction is called the denominator.	geometry Geometry is the mathematical study of points, lines, angles, and solids.	graph A graph is a diagram that shows relationships between things.	> greater than The mathematical symbol > means "greater than." When one number is greater than a second number, the first one is bigger than the second. For example, 4 is greater than 2, or 4 > 2.

1/2 half When something is divided into two equal parts, each of these two parts is half of the original object.	heart The heart is a shape that often symbolizes love.	heptagon A heptagon is a seven-sided figure.	hexaflexagon A hexaflexagon is a folded geometric figure that can be "flexed" to expose its many sides.	hexagon A hexagon is a six-sided figure. Beehives have hexagonal cells.
100 hundred One hundred is the number after 99 and before 101.	icosahedron An icosahedron is a twenty-sided geometric solid.	isosceles triangle An isosceles triangle has two sides that are the same length and two angles that are the same.	kite A kite is a four-sided figure in which the two pairs of adjacent sides have the same length.	< less than The mathematical symbol < means "less than." When one number is less than a second number, the first one is smaller than the second. For example, 1 is less than 2, or 1 < 2.
line segment A line segment is a portion of a line.	long division In long division, the dividend is divided by the divisor, resulting in a quotient plus a remainder.	5 4 6 6 5 4 4 6 5 magic square In a magic square, the rows, columns, and diagonals all add up to the same number.	mathematics Mathematics is the study of numbers, shapes, patterns, and logical reasoning.	1,000,000 million A million is a thousand thousands. The dinosaurs lived millions of years ago.
- minus The mathematical symbol - means "minus." Four minus three is written, 4 - 3.	Möbius strip A Möbius strip is a piece of paper with only one side!	1 x 2 = 2 2 x 3 = 6 multiplication Multiplication is a mathematical operation used to compute areas and do other calculations.	x multiply The mathematical symbol x means "multiply." Four times three is written, 4 x 3.	nine Nine is the number between eight and ten. There are nine players on a baseball team.

nonagon A nonagon is a nine-sided polygon.	number line Numbers correspond to points on a number line.	number Numbers tell you "how many" or "how much."	numerator The numerator is the top number in a fraction.	obtuse angle An obtuse angle is greater than ninety degrees.
octagon An octagon is an eight-sided figure. Stop signs are octagons.	octahedron An octahedron is an eight-sided geometric solid.	1, 3, 5, 7, 9, 11, ... odd number An odd number is not divisible by two.	one One is a small number.	1/2 one half When something is divided into two equal parts, each of these two parts is one half of the original object.
orb A ball-shaped object is an orb.	oval An oval is an egg-shaped figure.	parallel Parallel lines extend in the same direction, are always the same distance apart, and never meet.	parallelogram A parallelogram is a four-sided figure whose opposite sides are parallel.	pattern A pattern is something that is repeated.
pentagon A pentagon is a five-sided figure.	perimeter Perimeter is the distance around the edges of a figure. For example, the perimeter of a square with side length of a is a+a+a+a=4 times a.	perpendicular When two lines are perpendicular, they are at right angles (90 degrees).	pi Pi is the ratio of the circumference of a circle to the diameter of a circle (this ratio is the same for any size circle). Pi is roughly equal to 3.14159.	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.
. point A point is an exact location, a spot with no width or thickness.	polygon A polygon is a many-sided figure with straight edges.	polyhedron Polyhedra are solids whose faces are polygons.	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.

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 build by ancient Egyptians.	quadrilateral A quadrilateral is a four-sided figure. The square, rectangle, rhombus, trapezoid, kite, and parallelogram are quadrilaterals.	quotient The quotient is the answer in long division. The dividend divided by the divisor is the quotient (plus a remainder).	radius The radius is the distance from the center of a circle (or a sphere) to the edge.	1/2 ratio A ratio is the relationship between two numbers, as defined by the result you get when you divide one by the other.
rectangle A rectangle is a four-sided figure whose sides are at right angles to each other.	remainder The remainder is the fractional part of the answer in long division. The dividend divided by the divisor is the quotient plus the remainder.	rhombus A rhombus is a parallelogram with equal-length sides.	right angle A right angle looks like the corner of a square; it extends ninety degrees.	right triangle A right triangle has one angle that is a right angle (extending 90 degrees).
Roman numerals Thousands of years ago, in ancient Rome, the Romans used a system of numbers that we call Roman numerals. In this system, I=1. V=5, X=10, L=50, C=100, D=500, and M=1,000.	scalene triangle The sides of a scalene triangle are all different lengths.	second The second person or item comes after the first and before the third.	semicircle A semicircle is half a circle.	seven There are seven days in the week.
shapes Everything has a shape.	six Insects have six legs.	sphere A sphere is a ball-shaped object.	square A square has four, equally long sides which are at right angles to each other.	star A star is a shape that has many points.
1-1=0 5-3=2 subtraction Subtraction is the operation of taking one number away from another.	tally marks Tally marks are a quick way of keeping track of numbers in groups of five. One vertical line is made for each of the first four numbers; the fifth number is represented by a diagonal line across the previous four.	ten People have ten fingers and ten toes.	tetrahedron A tetrahedron is a pyramid formed by four triangles.	third The third person or item comes after the first and second.
13 ****** ******* thirteen Thirteen is the number after twelve (12) and before fourteen (14).	30 ********** ********** ********** thirty Thiry is the number after twenty nine (29) and before thirty one (31).	1,000 thousand One thousand is a whole number that is equal to 100 times 10.	three Three is the number between 2 and 4. A tricycle has three wheels. A triangle has three sides. A Triceratops has three horns. Tri means three!	torus A torus is a doughnut-shaped object.
trapezoid A trapezoid is a four-sided figure with exactly two parallel sides.	triangle A triangle is a geometric figure that has three sides.	12 ****** ****** twelve Twelve (12) is the number between eleven (11) and thirteen (13). Dozen is another word for twelve.	twenty There are twenty (20) apples above.	two We have two eyes, two ears, two arms, and two legs.
1 + 1 ≠ 3 unequal Two things are unequal if they are not the same.	Venn diagram A Venn diagram is a diagram that uses overlapping circles to show relationships among sets of things.	0 zero Zero is a number that stands for the absence of size or quantity.

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