# Natural Numbers

# Whole Numbers

# Integers

# Number Line

The number line is used to represent the set of real numbers. A representation of the number line is given below:

# Properties of Number Line

- The number line goes on till infinity in both directions. This is indicated by the arrows.
- Integers greater than zero are called positive integers. These numbers are to the right of zero on the number line.
- Integers less than zero are called negative integers. These numbers are to the left of zero on the number line.
- Â•The integer zero is neutral. It is neither positive nor negative.
- Â•The sign of an integer is either positive (+) or negative (âˆ’), except zero, which has no sign.
- Â•Two integers are the opposites if each of the two are at the same distance from zero, but on the opposite side of the number line. One will have a positive sign while the other a negative sign. In the number line above, +3 and âˆ’3 are labelled as opposites. In other words, the whole negative number scale looks like a mirror image of the positive number scale, with a number like âˆ’15 being at the same distance away from 0 as the number 15 is.
- Â•The number half-way between âˆ’1 and âˆ’2 is âˆ’1.5; just as the number halfway between 1 and 2 is 1.5.
- Â•We represent positive numbers without using a +ve sign.
For example, we would write 29.1 instead of +29.1. But when we talk of negative numbers, the sign must be there.