do one's sums

do one's sums (third-person singular simple present does one's sums, present participle doing one's sums, simple past did one's sums, past participle done one's sums)

1. (Britain, informal) This term needs a definition. Please help out and add a definition, then remove the text {{rfdef}}.

• “do your sums” in Longman Dictionary of Contemporary English, Longman.
• “do your sums” (UK) in Macmillan English Dictionary.