Yes, 5/6 is a rational number. A rational number is defined as any number that can be expressed as the quotient or fraction of two integers, where the denominator is not zero.
In the case of 5/6, both 5 and 6 are integers, and the denominator (6) is not zero. Therefore, 5/6 qualifies as a rational number. Additionally, rational numbers can include integers (like 5) as they can also be expressed as fractions (5/1, for example).