back-of-the-envelope calculation

back-of-the-envelope calculation

A calculation or mathematical formulation that is approximated in a quick, informal, and rough manner, as might be sketched out on a scrap of paper (such as the back of an envelope). When it came time to pay the bill, we had to do some back-of-the-envelope calculations to figure out who owed how much.
Farlex Dictionary of Idioms.
See also:
  • envelope
  • on the back of an envelope
  • rounding error
  • sketch out
  • how-d'ye-do
  • flow
  • nummers
  • sweat
  • sweats
  • yes, sirree
References in periodicals archive
After doing a full cost analysis on taking out a personal loan instead of just a back-of-the-envelope calculation, you may find your holiday or home improvement costs a lot more than you originally thought.
Scanlon's back-of-the-envelope calculation suggests the lakes could have persisted or hundreds or even a few thousand years.
Consider this back-of-the-envelope calculation of the Oregon program's cost to taxpayers.
Some regulators do engage in a back-of-the-envelope calculation by multiplying an average hourly wage rate and regulatory compliance hours, but many do not, in part because arriving at an acceptable value for an hourly wage rate is no small feat.
In fact, in a "back-of-the-envelope calculation", the International Energy Agency estimates that western oil sanctions cost Iran $40 billion in lost revenues in 2012 as crude exports fell to an average 1.5 million barrels per day over the year -- a decline of around 1 mbpd from 2011 levels (based on an average price of $111.70/barrel of Brent oil).
A back-of-the-envelope calculation reveals that these numbers rival diesel efficiency and if mogas is factored into the equation, flying a 912 iS-equipped aircraft is substantially less expensive than the equivalent 912 ULS.
"My own back-of-the-envelope calculation suggests a yield of between 4 and 15 kilotons."
A back-of-the-envelope calculation, assuming a $100 million figure, suggests that this would lead to only a $100 credit to the poorest one-third, which comes out to be about $8 per month.
A back-of-the-envelope calculation derived from Adelson's company's financial filings shows that that 83 per cent works out to $1.99 billion.
The decision will help a third of its home loan customers of more than 17 lakh in bringing down interest payments by as much as two percentage points, or a gain of about Rs 6,000 a month on a 20-year, Rs 50-lakh mortgage, a back-of-the-envelope calculation shows.
One source, who is not involved in the project but did a back-of-the-envelope calculation, estimated it would take blended rents of about $110 per foot for the project to break even.
If one calculates these percentage increases as national income projections over an 80-year period (providing for a 20-year delay before any school reform is completed and the newly proficient students begin their working careers), a back-of-the-envelope calculation suggests gains of nothing less than $75 trillion over the period.
A back-of-the-envelope calculation suggests Labour would lose 13 of their 29 seats in Wales, leaving them with fewer than half.
That means, by a back-of-the-envelope calculation, there is one cancer cell for every 100 quadrillion normal bone marrow cells nationwide per year, he said.
That amounts to 120 issues, several hundred articles, and, by a back-of-the-envelope calculation, over 3 million words--and counting.