The phrase "do a number on" generally means to harm or damage someone or something. The opposite of this phrase could be to heal, fix, repair, or mend. Antonyms for "do a number on" could also include positive actions that promote growth, improvement, or progress like nurture, support, encourage, uplift, or inspire. Using positive language and treating others with kindness and respect can help to counteract the negative effects of "doing a number on" someone, whether it be through words or actions. Choosing to act with intention and compassion can help to build stronger, more positive relationships and communities.