Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

$5\times23$
A number is prime if it has only two factors: 1 and itself. We know that the factors of 115 are 1, 5, 23, and 115. 5 is a prime number, so we can divide 115 by 5. $115\div5=23$ 23 is also a prime number. Therefore, the prime factorization of 115 is $5\times23$.