90 important Math terms and numeracy explained for primary students


Learning math is like learning a foreign language.  In order to be successful in Math, students must become fluent with the vocabulary.  To help children learn Math in a language that is not their first language, teachers and parents need to assess whether this is desirable and attempt to find meaningful, effective ways in which they are able to correctly use Mathematical terms and apply them to problem-solving.

As many parents have realized that throughout the time studying Math in English, your child will be introduced to a huge number of words and phrases, many of which may seem baffling – both to them and to you.

In this article, we list down the most important Math vocabulary words and concepts that every primary student should know. This list is designed to inform students, parents, and teachers of the vocabulary and meaning of terms in mathematics that students may have encountered in their primary school, in international Math contests, Math online learning sites… and will encounter when they transfer to post-primary education. 

Please note that this is not a comprehensive glossary of every basic mathematical term that could come up throughout your child’s primary school life, merely the key ones they will need to form solid foundations in the subject.

TermDefinitionDiagram/ Example
AAddendsNumbers are involved in an addition problem; a number that is added to another number
AdditionFinding the total, or sum, by combining two or more numbers.
Acute angleAn Acute Angle is less than 90°
AngleThe amount of turn between two lines around their common point (the vertex).
Ascending orderArranged from smallest to largest. Increasing.2, 4, 15, 31 are in ascending order.
AreaThe size of a surface. 
AverageA calculated “central” value of a set of numbers.
BBar chartA bar chart is a form of graph that displays information using rectangular bars to show value.
Bar modelA bar model is a method that uses diagrams of rectangular bars to represent maths problems in a visual way
CCircleA continuous curved line, the points of which are always the same distance from center point.
CircumferenceThe distance around the edge of a circle.
Circumference of Circle = 2πr
Complementary anglesTwo angles are complementary angles when they add up to 90°
Composite numberA whole number that can be made by multiplying other whole numbers.
ConeA solid (3-dimensional) object that has a circular base joined to a point by a curved side.
The pointed end of the cone is called the apex, whereas the flat surface is called the base.
DDecimalA decimal number (based on the number 10) contains a Decimal Point.
“forty-five and six-tenths” written as a decimal number
Declineto gradually become less, lower
Decomposing numberDecomposing is when we break the number apart
Descending orderArranged from largest to smallest. Decreasing.For example, 210, 52, 11, 9, 2 are in descending order.
DenominatorThe bottom number in a fraction.
DiagonalA line that goes from one corner to another, but is not an edge.
DiameterThe distance from one point on a circle through the center to another point on the circle. And it is twice the radius.
DifferenceDifference means to subtract one value from another
DividendThe number that you want to divide up.
When dividing by a certain number gives a whole number answer
For example, 10 is divisible by 5, because 10 ÷ 5 = 2 exactly
But 9 is not divisible by 2 because 9 ÷ 2 is 4 with 1 left over.
DivisionDivision is splitting into equal parts or groups.
DivisorThe number we divide by.
EEdgeAn edge is the name for lines created when two faces in a 3D shape meet.
EqualExactly the same amount or value
Even numberAny integer that can be divided exactly by 2 is an even number.
EquationA mathematical statement shows that both sides equal the other.For example, 12 – 5 = 3 + 4
Equilateral triangleA triangle with three equal sides and three equal angles.
Equivalent fractionThe fractions that have different numerator and denominator but are equal to the same value.
FFactorNumbers we can multiply together to get another number.For example, 2, 3, 4 and 6 are all factors of 12, and 12 can be divided into them exactly.
FewerSmaller quantity or amount.
FractionShows how many parts of a whole:
• the top number (the numerator) says how many parts we have.
• the bottom number (the denominator) says how many equal parts the whole is divided into
GGeometryThe branch of mathematics that deals with points, lines, shapes and space.
GreaterBigger.The symbol > means greater thanFor example, 7 > 4 shows that 7 is greater than 4.
HHypotenuseThe side opposite the right angle in a right-angled triangle.
HemisphereA hemisphere is the half sphere formed by a plane intersecting the center of a sphere.
HexagonA hexagon is a 6-sided polygon
IIncreaseMake something bigger (in size or quantity).
IntegerA whole number. It may be positive, negative, or zero.
Isosceles triangleA triangle with two equal sides and two equal angles across from them.
LLess thanSmaller.The symbol < means less than For example, 4 < 7 shows that 4 is less than 7.
LineA line is absolutely straight, has no thickness, extends in both directions without end.
MMeanFound by adding a set of values and dividing the total by the number of values in the set.For example, the mean of 2, 4, 5, 7 and 12 is 6 because (2 + 4 + 5 + 7 + 12) ÷ 5 = 6
MedianThe median of a set of numbers is the middle number in that list. The numbers in the list must first be sorted into ascending order.For example, the median of 1, 2, 3, 4, 5, 6, 7 is 4.
Mid pointThe middle point of a line segment. 
MinuendThe first number in a subtraction.
Mixed numberA whole number and a fraction combinedFor example, 5½ (five and a half) is a mixed number.
ModeThe mode of a set of numbers is the one that appears most often. For example, the mode of 2, 3, 4, 5, 5, 6, 7 is 5.
Multiple A multiple is the result of multiplying one integer by another.
MultiplicationThe basic idea of multiplication is repeated addition.For example: 5 × 3 = 5 + 5 + 5 = 15
NNegative numberLess than zero.
NumeratorTop number in a fraction.
Number lineA number line is a horizontal line, with numbers placed at equal  or segments along its length.
OObtuse angleAn Obtuse Angle is more than 90° but less than 180°
Odd numberAny integer that cannot be divided exactly by 2 is an odd number.
PPairTwo together. For example, {12,11} is a pair of numbers
Parallel2 lines that always have the same distance apart and never touching.
ParallelogramA Parallelogram is a flat shape with opposite sides parallel and equal in length.
PentagonA pentagon is a 5-sided Polygon
PercentagePercentage means ‘out of 100’ and is used to show a number or ratio expressed as a fraction of 100.For example, this 300.000VND  jacket had 20% off in the Christmas sale.
PerimeterThe total distance around the outside of a polygon. This distance is obtained by adding together the units of measure from each side.For example, the perimeter of this rectangle is 7+3+7+3 = 20
PerpendicularTwo lines or line segments intersecting to form a right angle.
PolygonA polygon is any 2D shape with straight, closed sides. 
Prime numberA prime number is any number greater than 1 that can only be divided equally by itself and 1.
PrismA prism is a 3D shape with two identical flat sides and ends.
ProductThe answer when two or more values are multiplied together.
QQuotientThe answer after we divide one number by another.For example, in 12 ÷ 3 = 4, 4 is the quotient.
QuadrilateralA flat shape with four straight sides.
RRadiusThe distance from the center to the circumference of a circle
RatioA ratio shows the relative sizes of two or more values.For example, the ratio of boys to girls was 2:1, meaning there are two boys for every one girl.
RemainderAn amount left over after division
Right angleA right angle is an internal angle which is equal to 90°
RhombusA Rhombus is a flat shape with 4 equal straight sides.
SScalene triangleNo equal sidesNo equal angles
SequenceA sequence is a list of things (usually numbers) that are in order.
SetA set is a collection of things, usually numbers. 
SphereAn object shaped like a round ball
SubtractionTaking one number away from another.
SubtrahendA quantity or number to be subtracted from another.
SumThe result of adding two or more numbers.
Supplementary anglesThe two angles are supplementary angles when they add up to 180°
SymmetryWhen a picture or shape is the same on both sides, we call it ‘symmetrical’
TTrapezoidA trapezoid is a 4-sided flat shape with straight sides that has a pair of opposite sides parallel
TriangleA triangle has three sides and three angles right arrow. The three angles always add to 180°
UUnequalNot equal.
VVertexA point where two or more line segments meet. A corner.
VolumeThe volume is the amount of space an object occupies, especially 3D shapes.For example, the volume is 10 × 4 × 5 = 200 units3
WWeightHow heavy something is.
Whole numberWhole numbers are simply the numbers 0, 1, 2, 3, 4, 5, … (no negative, fractional or decimal parts)
Word problemsMathematical exercises presented in ordinary language rather than in mathematical notation. The most common types of word problems are distance problems, age problems, work problems, percentage problems, mixtures problems and numbers problems.For example,
Ann is three times as old as her little brother Bob. In five years, she will be only twice as old. How old are they now?

>>> Parents can also download our free printable set of Math flashcards, and read the detailed guidance of how to use them with your child here: https://blog.e2.com.vn/use-flashcards-to-teach-your-kids-math-vocab/

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