napkin math
Noun
Meaning
napkin math (uncountable)
(Canada, US) The act of performing quick mathematics often as a means of estimation, as if done on the back of a napkin (or in one's head).
Noun
napkin math (uncountable)
(Canada, US) The act of performing quick mathematics often as a means of estimation, as if done on the back of a napkin (or in one's head).