The notation "φ(5)" refers to the Euler's totient function, which counts the number of positive integers up to a given integer that are relatively prime to it. In this case, φ(5) calculates how many integers from 1 to 5 do not share any common factors with 5, other than 1. Since 5 is a prime number, the integers 1, 2, 3, and 4 are all relatively prime to it. To compute φ(5), we find that the integers 1, 2, 3, and 4 are indeed relatively prime to 5. Therefore, φ(5) equals 4, indicating that there are four integers less than or equal to 5 that do not share any factors with it. This property of the totient function is significant in number theory and has applications in areas such as cryptography and modular arithmetic.