### Theory:

A number that can expressed as $$a / b$$, where $$a$$ and $$b$$ are integers and $$b ≠ 0$$ is known as a rational number.
Example:
• $$-2/3$$
• $$6/7$$
• $$-3/1$$
Important!
Any number divided by $$0$$ is not a rational number.
• $$4/0$$ is not a rational number. Hence it is an undefined number.
If there are $$10$$ apples to be divided for $$4$$ children, it is not possible to give $$3$$ complete apples to each one. But, if we cut $$2$$ apples into half, then there will be $$4$$ half pieces and $$8$$ full apples. So each child would get $$2$$ full and $$1$$ half piece of apple.