Glossary

Can be divided by a number without leaving a remainder. For example, 20 is divisible by 4 because 20 ÷ 4 = 5 (no remainder).

The number that is being divided into the dividend in a division problem. In the problem 8 ÷ 2 = 4, 2 is the divisor.

A notation that represents repeated multiplication using a base and an exponent. For example, 2⁴ is notation that means 2 • 2 • 2 • 2. This notation tells you that 2 is used as a factor 4 times. 2⁴ = 16. (Also called exponential form.)

A number that is multiplied by another number or numbers to get a product. For example, in the equation 4 • 5 = 20, 4 and 5 are factors.

A pair of numbers whose product is a given number. For example, 2 and 15 are a factor pair of 30 because 2 •15 = 30. Both 2 and 15 are factors of 30.

An expression in which a whole number is combined with a proper fraction. For example 5

is a mixed number.

The result when two numbers are multiplied. For example, the product of 4 • 5 is 20.

A number that when multiplied by a given number gives a product of 1. For example, and are reciprocals of each other.

Denominators that are different from each other. For example the fractions and have different denominators, one denominator being 4 and the other denominator being 8.

common denominator	A number that is a multiple of all of the denominators in a group of fractions.
composite number	A natural number that has at least one factor other than 1 and itself.
denominator	The bottom number of a fraction that tells how many equal parts are in the whole.
divisibility test	A rule that tells quickly whether dividing a number by another number can be done without leaving a remainder.
divisible	Can be divided by a number without leaving a remainder. For example, 20 is divisible by 4 because 20 ÷ 4 = 5 (no remainder).
divisor	The number that is being divided into the dividend in a division problem. In the problem 8 ÷ 2 = 4, 2 is the divisor.
equivalent fractions	Two or more fractions that name the same part of the whole.
even number	A whole number that is divisible by 2.
exponential notation	A notation that represents repeated multiplication using a base and an exponent. For example, 2⁴ is notation that means 2 • 2 • 2 • 2. This notation tells you that 2 is used as a factor 4 times. 2⁴ = 16. (Also called exponential form.)
factor	A number that is multiplied by another number or numbers to get a product. For example, in the equation 4 • 5 = 20, 4 and 5 are factors.
factor pair	A pair of numbers whose product is a given number. For example, 2 and 15 are a factor pair of 30 because 2 •15 = 30. Both 2 and 15 are factors of 30.
factor tree	A diagram showing how a number can be written as factors, and those factors written as a product of factors, and so on until only prime numbers are used.
fraction	An expression used to refer to a part of a whole.
improper fraction	A fraction in which the numerator is equal to or greater than the denominator.
least common denominator	(LCD) The least, or smallest, number that is a multiple of all the denominators in a group of fractions.
least common multiple	(LCM) The least, or smallest, number that is a multiple of two or more numbers.
like denominators	Denominators that are the same.
lowest terms	A fraction is in lowest terms if the numerator and denominator have no common factors other than 1.
mixed number	An expression in which a whole number is combined with a proper fraction. For example 5 is a mixed number.
multiple	Any number that has a given number as a factor. For example, 4, 8, 16, and 200 are multiples of 4, because 4 is a factor of each of these numbers.
natural number	The numbers 1, 2, 3, 4 and so on. Also called counting numbers.
numerator	The top number of a fraction that tells how many parts of a whole are being represented.
prime factorization	A number written as the product of its prime factors.
prime number	A natural number with exactly two factors: 1 and the number itself.
product	The result when two numbers are multiplied. For example, the product of 4 • 5 is 20.
proper fraction	A fraction in which the numerator is less than the denominator.
reciprocal	A number that when multiplied by a given number gives a product of 1. For example, and are reciprocals of each other.
simplest form	A fraction is in simplest form if the numerator and denominator have no common factors other than 1.
unlike denominators	Denominators that are different from each other. For example the fractions and have different denominators, one denominator being 4 and the other denominator being 8.