Yes, 12/4 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 this case, 12 and 4 are both integers, and 4 is not zero.
When we simplify 12/4, we get 3, which is also an integer. Therefore, both 12/4 and 3 are rational numbers. This means that any fraction in which both the numerator and the denominator are whole numbers qualifies as a rational number, and since 12/4 meets that criterion, it is indeed classified as such.