How do you know that the additive inverse of -20 is 20? Algebra Properties of Real Numbers Additive Inverses and Absolute Values 1 Answer seph Nov 22, 2014 A number #N#'s additive inverse #N'# is a number that when added to #N#, will result to the additive identity, which is 0. #20 + N' = 0# #=> N' = -20# Answer link Related questions What are absolute values? What is the absolute value of -10 and 10? How do you evaluate #|2-8|#? How do you simplify #-|-1|#? What is the additive inverse property? What is the absolute value of -9? How do you simplify #x = - abs6^2 - abs(-4 + 7) *7#? How do you simplify #abs( -11 +1)#? How do you simplify #abs6-abs(-3)#? How do you simplify #abs(1/5-1/3)#? See all questions in Additive Inverses and Absolute Values Impact of this question 4226 views around the world You can reuse this answer Creative Commons License