An integer is a number that has no fractional part, and no digits after the decimal point. An integer can be positive, negative or zero. (Compare this to real numbers than can have digits after the point and can have fractional parts)

Example integers: 12 , 34 , -4 , 0

The following are real numbers and are not integers:

  • 1.23 (cannot have decimal places)
  • 12½ (cannot have a fractional part).

Try this Drag the orange dot below to move it along the number line. Note how it only stops at the integers.

Whole numbers and counting numbers

Whole numbers (sometimes called 'counting numbers') are like integers, but they cannot be negative. They are usually used to indicate the number of objects. Example: 12 students.


Real numbers can be converted to integers by rounding. This means removing the decimal digits and adjusting the result to be the nearest integer to the original number. See Rounding for more.

Pages referring to 'integer'

An overview of the types of numbers that are used in math. Links to other pages explaining each type in depth. Explains also that some numbers are not numbers at all.

Other number topics

Scalar numbers

Counting numbers

Numbers that have factors

Special values