Idenify which condition is necessary for a number to be rational

Answer 1

A number is considered rational if it can be expressed as the ratio of two integers, where the denominator is not zero. Specifically, a number \( r \) is rational if there exist integers \( a \) and \( b \) (with \( b \neq 0 \)) such that:

\[ r = \frac{a}{b} \]

In summary, the necessary condition for a number to be rational is that it can be represented as the quotient of two integers, with the denominator being non-zero.