back-of-the-envelope

Etymology
A reference to a calculation or an idea that occurs to one being jotted down on an available scrap of paper, such as the back of an envelope.

Adjective

 * 1)  Especially of a calculation, estimation, or other reasoning, or an idea: approximate, rough, simplified.

Translations

 * Chinese:
 * Mandarin: 粗略的
 * Danish:
 * Finnish: ruutupaperi
 * French:, ,
 * German:, ,
 * Macedonian:
 * Portuguese: à pressa, em cima do joelho
 * Russian: