Theory:

A rational number is one that can be written as the ratio of two integers.
Example:
i. $$6 = 12/2$$.
ii. $$9 = 27/3$$.
iii. $$4 = 16/4$$.
A number line is a way to visualize numbers by placing them along a line that shows their relative sizes.

Order to represent the rational number on the number line:
• We draw a line and mark a point $$O$$ on it to represent the rational number $$0$$.
• The positive rational number will be represented on the number line to the right of $$O$$.
• The negative rational numbers will be represented on the number line to the left of $$O$$.
• If we mark a point $$A$$ on the line to the right of $$O$$ to represent $$1$$, then $$OA =$$ $$1$$ unit.
• Similarly, if we choose a point $$A'$$ on the line to the left of $$O$$ to represent $$-1$$ then $$OA' =$$ $$-1$$ unit.

Now, we are going to representing the rational number $$1/2$$ on the number line. For this, we divide the segment $$OA$$ into equal parts. Let $$P$$ be the midpoint of segment $$OA$$. Then, $$OP = PA = 1/2$$ and also we divide the segment $$OA'$$ into equal parts. In this $$P'$$ be the midpoint of segment $$OA'$$, then $$OP'= P'A = -1/2$$.