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1
Back of Envelope Office Space Conundrum
Back of Envelope Office Space Conundrum
::2011/04/18::
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2
Anthony Zee: Back-of-the-Envelope Calculations
Anthony Zee: Back-of-the-Envelope Calculations
::2012/03/04::
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3
Back of the Envelope - Episode 1 - Garbage Calculations
Back of the Envelope - Episode 1 - Garbage Calculations
::2013/02/21::
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4
Back of the Envelope Calculations
Back of the Envelope Calculations
::2011/01/27::
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5
Back of the Envelope - Episode 2 - Addendum
Back of the Envelope - Episode 2 - Addendum
::2013/05/04::
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6
Anna Salamon: "How Much it Matters to Know What Matters: A Back of the Envelope Calculation"
Anna Salamon: "How Much it Matters to Know What Matters: A Back of the Envelope Calculation"
::2012/02/21::
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7
Estimating the Tangential Velocity of Earth
Estimating the Tangential Velocity of Earth
::2011/10/08::
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8
Excise cut likely to impact Q4 margins of OEMs
Excise cut likely to impact Q4 margins of OEMs
::2014/03/27::
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9
Back of the Envelope - Episode 3 - Survival Garden
Back of the Envelope - Episode 3 - Survival Garden
::2013/05/07::
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10
How much coal per kWh?
How much coal per kWh?
::2013/08/25::
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11
Gian Fulgoni Chairman & Co-founder, comScore (Festival of Media 2009) Part 1
Gian Fulgoni Chairman & Co-founder, comScore (Festival of Media 2009) Part 1
::2010/08/10::
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12
Gian Fulgoni Chairman & Co-founder, comScore (Festival of Media 2009) Part 2
Gian Fulgoni Chairman & Co-founder, comScore (Festival of Media 2009) Part 2
::2010/08/10::
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13
HydroPad Demo
HydroPad Demo
::2012/03/23::
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14
Excel modeling perfection training - 1. Introduction (1 of 8)
Excel modeling perfection training - 1. Introduction (1 of 8)
::2011/10/21::
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15
HUMANITARIAN CRISIS ON THE SOUTH BORDER, KIDS CROSSING UP FROM GUATEMALA
HUMANITARIAN CRISIS ON THE SOUTH BORDER, KIDS CROSSING UP FROM GUATEMALA
::2014/06/12::
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16
Frontiers of Science
Frontiers of Science
::2007/04/25::
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17
Dr. Frank Wang calculates power generated by Hoover Dam
Dr. Frank Wang calculates power generated by Hoover Dam
::2011/07/19::
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18
My Voyage from Migrant Farm Worker to Brain Surgeon
My Voyage from Migrant Farm Worker to Brain Surgeon
::2012/01/24::
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The Dangers of Trampolines - My True Confession: SingingDrJosh - The Singing Pediatrician
The Dangers of Trampolines - My True Confession: SingingDrJosh - The Singing Pediatrician
::2012/12/02::
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Stock Selection Process For Momentum Breakout Stocks Part 3
Stock Selection Process For Momentum Breakout Stocks Part 3
::2013/09/10::
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21
Heath Ceramics - Beautiful MUSA Tableware, Responsibly (extended version)
Heath Ceramics - Beautiful MUSA Tableware, Responsibly (extended version)
::2011/10/11::
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The best (scripted) wedding toast ever!
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::2012/10/07::
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Straight Up-Derivatives, Bailouts and YOU Part 1
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::2009/01/29::
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24
Heath Ceramics - Beautiful MUSA Tableware, Responsibly
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::2011/10/11::
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25
Karl Johanson
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::2008/12/01::
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26
buyMUSA: We Can Do This (:30)
buyMUSA: We Can Do This (:30)
::2011/09/21::
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27
buyMUSA: We Can Do This (:60)
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::2011/09/04::
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28
Estimating Ammonia Emissions from Livestock Using Low-Cost, Time-Averaged Concentration Measurements
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::2013/05/29::
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::2008/04/21::
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Dr.ROWLEY explains RATIONAL behind PNM Commitment to RAPID RAIL sysyem!
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::2012/10/05::
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31
Which five A1 companies pass Roger Montgomery
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::2011/06/16::
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32
MetaMo Training [Thai ver.] (5/6): BoE (Back of the Envelope)
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::2014/07/06::
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::2012/02/10::
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Survival in the Margins of the Singularity? - Anna Salamon [UKH+]
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::2011/02/02::
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How does Roger Montgomery quickly calculate cash flow?
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::2011/06/03::
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AGI 2011: The Future of AGI Workshop Part 1 - Ethics of Advanced AGI
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::2011/08/31::
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How to Calculate Price Elasticity of Demand (PED)
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::2011/08/14::
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::2013/03/15::
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::2012/05/30::
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Peter Norvig of Google on The History and Future of Technological Change
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::2012/02/21::
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::2013/11/21::
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The Science of Iron Man
The Science of Iron Man
::2013/04/22::
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43
nanoHUB-U Fundamentals of AFM L3.1: AFM-The Instrument - The Water Meniscus
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::2014/06/02::
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Turbo-charging the Mind
Turbo-charging the Mind
::2012/09/18::
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45
Tony Yayo - King Of The Pyrex - HQ - 320
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::2010/02/10::
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nanoHUB-U Fundamentals of AFM L3.3: AFM-The Instrument - AFM Components
nanoHUB-U Fundamentals of AFM L3.3: AFM-The Instrument - AFM Components
::2014/06/02::
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6. The Origin and Maintenance of Genetic Variation
6. The Origin and Maintenance of Genetic Variation
::2009/09/02::
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48
Intermediate Microeconomics: Income Elasticity
Intermediate Microeconomics: Income Elasticity
::2014/02/07::
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Data-Driven Donor Management
Data-Driven Donor Management
::2012/09/19::
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50
CFAR - Anna Salamon on Rationality
CFAR - Anna Salamon on Rationality
::2013/04/28::
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RESULTS [51 .. 101]
From Wikipedia, the free encyclopedia
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A back-of-the-envelope calculation is a rough calculation, typically jotted down on any available scrap of paper such as the actual back of an envelope. It is more than a guess but less than an accurate calculation or mathematical proof. The defining characteristic of back-of-the-envelope calculations is the use of simplified assumptions. A similar phrase is "back of a napkin", which is also used in the business world to describe sketching out a quick, rough idea of a business or product.[1] The usual idiom, in British English, is "back of a fag packet".

History[edit]

In the hard sciences, back-of-the-envelope calculation is often associated with physicist Enrico Fermi,[2] who was well known for emphasizing ways that complex scientific equations could be approximated within an order of magnitude using simple calculations. He went on to develop a series of sample calculations, which are called "Fermi Questions" or "Back-of-the-Envelope Calculations" and used to solve Fermi problems.[3][4]

Fermi was known for getting quick and accurate answers to problems that would stump other people. The most famous instance came during the first atomic bomb test in New Mexico on 16 July 1945. As the blast wave reached him, Fermi dropped bits of paper. By measuring the distance they were blown, he could compare to a previously computed table and thus estimate the bomb energy yield. He estimated 10 kilotons of TNT; the measured result was 18.6.[5][not in citation given]

Another example is Victor Weisskopf's pamphlet Modern Physics from an Elementary Point of View.[6] In these notes Weisskopf used back-of-the-envelope calculations to calculate the size of a hydrogen atom, a star, and a mountain, all using elementary physics.

Examples[edit]

Nobel laureate Charles Townes describes in a video interview for the University of California, Berkeley on the 50th anniversary of the laser, how he pulled an envelope from his pocket while sitting in a park and wrote down calculations during his initial insight into lasers.[7]

See also[edit]

Notes and references[edit]

External links[edit]

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