120 as a fraction is written as 120/1. This is because any whole number can be expressed as a fraction by placing it over 1. In this case, 120 is the numerator and 1 is the denominator.
If you need to simplify this fraction further, you would look for common factors between the numerator and the denominator. However, since 120 and 1 have no common factors other than 1, the fraction 120/1 is already in its simplest form.