back-of-an-envelope

Definitions

Adjective. [C2]

Examples

“On one defense item, somebody kept referring to it as a back-of-an-envelope cost⟳ estimate⟳. Do you have⟳ a back-on-an-envelope cost⟳ estimate⟳?”

“The reader will not need⟳ to be warned that the calculations involved are of the back of an envelope type⟳ and statements of the form⟳ ‘a equals b’ should be read⟳ ‘a equals b approximately’ or even ‘with a bit of luck, a and b will be of the same order⟳ of magnitude’.”

“Misapplying a basic feature of diffusion theory, [Werner] Heisenberg arrived at an impossibly high figure⟳ for a critical mass of pure U235. This was done by means of a seductively simple "back of an envelope" calculation in 1940, […]”

“Now, those Treasury mandarins unfamiliar with the railway might assume⟳ on the back of an envelope that if only 80% of trains are running, then that will cost⟳ 20% less. If only it were that simple.”

CEFR level