Group of Numbers

Integers

... -3, -2, -1, 0, 1, 2, 3,... (all the whole numbers together with their opposites).

Whole Numbers

0,1,2,3,4,........ The natural number together with 0.

Composite Number

A natural number greater than 1 that is not a prime number. (An alternate definition is a natural number that has at least three different divisors.) The first seven composite numbers are 4, 6, 8, 9, 10, 12, 14.

Prime Number

A natural number greater than 1, and that only has 1 and itself as divisors. (An alternate definition is a natural number that has exactly two different divisors.) The first seven prime numbers are 2, 3, 5, 7, 11, 13, 17.

Real Numbers

All the rational and irrational numbers.

Rational Number

All values that can be expressed in the form , where a and b are integers and b ≠ 0, or when expressed in decimal form, the expression either terminates or has a repeating pattern. Examples: 41/2 = 9/2; therefore, 41/2 is a rational number. 0.3 is a terminating decimal; therefore, 0.3 is a rational number. 0.134343434... is a repeating decimal; therefore, 0.134343434... is a rational number.

Irrational Number

Any value that exists but is not rational. Examples: π The decimal name for pi starts out 3.14159265... The decimal name for pi does not terminate nor does it have a repeating pattern. The decimal name for the square root of 2 starts out 1.41421356... The decimal name for the square root of 2 does not terminate nor does it have a repeating pattern.

Natural Numbers

Counting numbers: 1,2,3,4,5...... The number 0 is not a natural number.

Square Numbers

The results of taking integers and raising them to the 2nd power (squaring them). An alternate definition is the result when numbers are multiplied by themselves. The first seven positive square numbers are 1, 4, 9, 16, 25, 36, 49. Examples: (-3)2 = 9; therefore, 9 is a square number. (0)2 = 0; therefore, 0 is a square number, but is not a positive square number.

Cube Numbers

The results of taking integers and raising them to the 3rd power (cubing them). The first seven positive cube numbers are 1, 8, 27, 64, 125, 216, 343. Examples: (-3)3 = -27; therefore, -27 is a cube number. (0)3 = 0; therefore, 0 is a cube number.