A rational number is defined as a number that can be expressed as the quotient of two integers, where the denominator is not zero.
1.345 is a rational number because it can be expressed as a fraction: \( \frac{1345}{1000} \).
On the other hand, \( \sqrt{6} \) is an irrational number because it cannot be expressed as a fraction of two integers. The decimal expansion of \( \sqrt{6} \) goes on forever without repeating.
Therefore, 1.345 is the rational number.