This problem is about absolute value.
Four important notes to remember are:
• Absolute value is the modulus of a number, that is, includes only the number without any signs.
• The absolute value of a number can be positive, when the number is positive, that is
• The absolute value can be negative if the number is negative
• The absolute value of zero is zero.
There you have it, those are 4 important notes to keep in mind about absolute value.
On the other hand, "the additive" would refer to a wide variety of subjects, so, there's a word missing to complete the question.