Opposite numbers are also known as additive inverses.
ɑ p ə z ɪ t WORD_BOUNDARY n ʌ m b ə ɹ z WORD_BOUNDARY ɑ ɹ WORD_BOUNDARY ɔ l s oʊ WORD_BOUNDARY n oʊ n WORD_BOUNDARY æ z WORD_BOUNDARY æ d ɪ t ɪ v WORD_BOUNDARY ɪ n v ɜː s ɪ z WORD_BOUNDARY