
Base Ten
System in which ten digits are used in combination to represent all numbers. The system also uses the concept of place value, wherein each place has a value greater by a factor of 10 than the value of the place to its right. The digit in each place represents a number that is equal to that numeral times 10 raised to a certain power. For example, the "5" in "6,589" represents 5×10^{2}.

Composite
A whole number that has at least one factor besides 1 and itself; e.g. any whole number greater than 1 and not prime.

Divisible
A number is divisible by another number if it can be divided equally by that number; that is, if it yields a whole number when divided by that number. 12 is divisible by 4 because 12/4 = 3, and 3 is a whole number. 12 is not divisible by 10, because 12/10 = 1.2, and 1.2 is not a whole number.

Decimal System
Our system of numeration. The digits 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9, used in combination, represent all numbers.

Factor
A number by which another number is divisible. 1, 2, 3, and 6 are all factors of 6, because 6/1, 6/2, 6/3, and 6/6 are all whole numbers.

Greatest Common Factor
The greatest (largest) number that divides two or more given numbers.

Least Common Multiple
The smallest number that is divisible by two or more given numbers.

Multiple
A number that can be obtained by multiplying a given number by a whole number. 6, 9, and 12 are all multiples of 3, because 3×2 = 6, 3×3 = 9, and 3×4 = 12. If a is a factor of b, then b is a multiple of a.

Place Value
The value of a digit, based on where it appears in a numeral. The value of each position in a numeral is ten times the value of the position to its right. The numeral 30,482 has a "2" in the ones place, an "8" in the tens place, a "4" in the hundreds place, a "0" in the thousands place, and a "3" in the ten thousands place. The number 1.567 has a "1" in the ones place, a "5" in the tenths place, a "6" in the hundredths place, and a "7" in the thousandths place.

Prime
A positive whole number divisible only by 1 and itself. Following are the first fifteen prime numbers: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47 ... (Note: 1 is not considered prime).

Prime Factorization
A number written as the product of its prime factors.

Relatively Prime
Two numbers that have no common prime factors and thus have a greatest common factor of 1. For example, 64 and 295 are relatively prime, since they share no prime factors.

Whole Number
The set of numbers which includes zero and all the counting numbersno fractions or decimals. 0, 1, 2, 3, 4, 5, 6, ...