Both 3 and 120 are integers. An integer is just a positive or negative whole number. When we have a number like 123.45, the integer part of this number would be 123. An integer doesn't have a measure like pounds, dollars, feet, inches, seconds, miles, hours, etc., it's just a pure whole number, but it can be applied to a measure, like $3 a pound, 10 apples, 120mph, 120 days, etc.