No, not every multiple of 5 is a composite number. A composite number is defined as a natural number greater than 1 that is not prime; in other words, it has more divisors than just 1 and itself.
Multiples of 5 include numbers like 5, 10, 15, 20, and so on. Among these, the number 5 is not composite; it is actually a prime number because it has exactly two distinct positive divisors: 1 and 5. However, multiples of 5 such as 10, 15, and 20 are composite because they have additional divisors.
In summary, the statement that every multiple of 5 is composite is incorrect since the first multiple, which is 5 itself, is a prime number.