What is a number line?

Number Line

The number line is a the concept about the meaning of mathematical operations. It is either horizontal or vertical line, with major divisions marked by the positive (+) and negative (-) whole numbers in a opposite direction. The entire range of whole numbers covered by the number line are also known as the integers.

In basic mathematics, it is a picture of horizontal straight line that divided into two symmetric half from its point of origin, zero (0) and stuff with points in which each points correspond to a whole number or real number.  

In between the whole number integers shown, there are other numbers, such as half, thirds, and quarters. These are ratios formed by dividing any integer by a nonzero integer. Together with the natural numbers—zero and the positive whole numbers, which are effectively ratios divided by 1—they form the rational numbers. These are marked by finer and finer subdivisions of the number line.

But do the rational numbers complete the number line? It turns out that almost all the numbers between zero and one cannot be written as ratios. These are known as irrational numbers, numbers whose decimal representations never stop and are not eventually repeating. The complete set of rationals and irrationals together are known as the real numbers.