Rational numbers are, by definition, numbers that can be made by dividing two integers. Any number that can be expressed as a fraction is a rational number, for example

"0.5" can be expressed as the quotient between "1" and "2", so it is a rational number
The number "pi", for example, cannot be expressed as a fraction, so it is called an irrational number.
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The fraction:

Is the quotient between two whole numbers "4" and "43", so it can be considered a rational number.