number-system Vocabulary
JamWise Education Team·Updated March 2026
The number-system strand is a core part of the K-8 math curriculum. It encompasses 25 vocabulary terms that students encounter as they progress from kindergarten through 8th grade. Each term builds on previous knowledge, creating a spiral of deepening understanding that prepares learners for increasingly complex concepts.
Understanding number-system vocabulary is essential for classroom discussions, assessments, and real-world application. Below you will find every term organized by grade level, so teachers and parents can quickly identify which words are appropriate for their students and explore definitions tailored to each developmental stage.
6th Grade
(16 terms)
Absolute value
The absolute value of a number is its distance from 0 on the number line. It is always zero or positive. The absolute value of -5 is 5.
Additive inverse
A number and its opposite. Their sum is always zero. The additive inverse of 5 is -5, because 5 + (-5) = 0.
Common factor
A number that divides evenly into two or more numbers. For example, 3 is a common factor of 6 and 15.
Coordinate plane
A flat surface formed by two number lines that cross at a right angle. The horizontal line is the x-axis and the vertical line is the y-axis.
Factors
Numbers that are multiplied together to get a product. The factors of 12 are 1, 2, 3, 4, 6, and 12.
Greatest common factor
The greatest common factor (GCF) of two whole numbers is the largest number that divides evenly into both. The GCF of 12 and 18 is 6.
Integer
The set of whole numbers and their opposites: ... -3, -2, -1, 0, 1, 2, 3 ... Integers do not include fractions or decimals.
Least common multiple
The least common multiple (LCM) of two whole numbers is the smallest number that is a multiple of both. The LCM of 4 and 6 is 12.
Long division
A step-by-step method for dividing numbers that builds the answer one digit at a time. It works for dividing large numbers and decimals.
Negative number
A number that is less than zero. Negative numbers appear to the left of zero on a horizontal number line.
Opposite
Two numbers that are the same distance from 0 on a number line but on different sides. The opposite of 4 is -4.
Positive number
A number that is greater than zero. Positive numbers appear to the right of zero on a horizontal number line.
Quadrant
One of the four sections of a coordinate plane created by the x-axis and y-axis. Quadrants are numbered I, II, III, and IV going counterclockwise from the upper right.
Rational number
A number that can be written as a fraction or the opposite of a fraction. This includes integers, fractions, and terminating or repeating decimals.
Reciprocal
The reciprocal of a number is 1 divided by that number. The reciprocal of 3 is 1/3, and the reciprocal of 2/5 is 5/2. A number times its reciprocal always equals 1.
Sign
Whether a number is positive or negative. Positive numbers have a positive sign (+), negative numbers have a negative sign (-). Zero has no sign.
7th Grade
(6 terms)Absolute value
The distance a number is from zero on the number line. Absolute value is always positive or zero. Written as |x|.
Additive inverse
Two numbers whose sum is zero. For any number a, its additive inverse is -a. The additive inverse of -7 is 7, because -7 + 7 = 0.
Complex fraction
A fraction where the numerator, denominator, or both contain a fraction. For example, (1/2)/(3/4) is a complex fraction.
Rational number
Any number that can be expressed as a fraction a/b where a and b are integers and b is not zero. This includes positive and negative fractions, integers, and terminating or repeating decimals.
Repeating decimal
A decimal in which one or more digits repeat forever. The fraction 1/3 = 0.333... is a repeating decimal, written as 0.3 with a bar over the 3.
Terminating decimal
A decimal that ends after a finite number of digits. The fraction 1/4 = 0.25 is a terminating decimal.
8th Grade
(10 terms)
Cube root
A number that, when used as a factor three times, gives the original number. The cube root of 27 is 3, because 3 × 3 × 3 = 27. Written as ∛27.
Integer
A whole number or its negative. The integers are ..., -3, -2, -1, 0, 1, 2, 3, ... They do not include fractions or decimals.
Irrational number
A number that cannot be written as a fraction of two integers. Its decimal form goes on forever without repeating. Pi and the square root of 2 are irrational.
Perfect square
A whole number that is the square of another whole number. 1, 4, 9, 16, 25, and 36 are perfect squares.
Rational number
A number that can be written as a fraction p/q where p and q are integers and q is not zero. Includes integers, fractions, and terminating or repeating decimals.
Real number
Any number on the number line, including both rational and irrational numbers. Every point on the number line corresponds to a real number.
Repeating decimal
A decimal in which a digit or group of digits repeats forever. Written with a bar over the repeating part. For example, 1/3 = 0.333... = 0.3̄.
Square root
A number that, when multiplied by itself, gives the original number. The square root of 25 is 5, because 5 × 5 = 25. Written as √25.
Terminating decimal
A decimal that ends after a finite number of digits. For example, 1/4 = 0.25 and 3/8 = 0.375 are terminating decimals.
Truncate
To shorten a decimal by cutting off digits after a certain place without rounding. Truncating 3.14159 to two decimal places gives 3.14.