1
Back of the Envelope Calculations
Back of the Envelope Calculations
DATE: 2012/08/23::
2
Anthony Zee: Back-of-the-Envelope Calculations
Anthony Zee: Back-of-the-Envelope Calculations
DATE: 2012/03/04::
3
Back of the Envelope - Episode 1 - Garbage Calculations
Back of the Envelope - Episode 1 - Garbage Calculations
DATE: 2013/02/21::
4
Back of the Envelope Calculations
Back of the Envelope Calculations
DATE: 2011/01/27::
5
Back of Envelope Office Space Conundrum
Back of Envelope Office Space Conundrum
DATE: 2011/04/18::
6
Back of the Envelope - Episode 3 - Survival Garden
Back of the Envelope - Episode 3 - Survival Garden
DATE: 2013/05/07::
7
Estimating the Tangential Velocity of Earth
Estimating the Tangential Velocity of Earth
DATE: 2011/10/08::
8
Back of the Envelope - Episode 2 - Addendum
Back of the Envelope - Episode 2 - Addendum
DATE: 2013/05/04::
9
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"
DATE: 2012/02/21::
10
Mirada targeting 4mln cable customers in Mexico
Mirada targeting 4mln cable customers in Mexico
DATE: 2015/02/17::
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The Dangers of Trampolines - My True Confession: SingingDrJosh - The Singing Pediatrician
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How much coal per kWh?
How much coal per kWh?
DATE: 2013/08/24::
13
Frontiers of Science
Frontiers of Science
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Excel modeling perfection training - 1. Introduction (1 of 8)
Excel modeling perfection training - 1. Introduction (1 of 8)
DATE: 2011/10/21::
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Gian Fulgoni Chairman & Co-founder, comScore (Festival of Media 2009) Part 1
Gian Fulgoni Chairman & Co-founder, comScore (Festival of Media 2009) Part 1
DATE: 2010/08/10::
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Stock Selection Process For Momentum Breakout Stocks Part 3
Stock Selection Process For Momentum Breakout Stocks Part 3
DATE: 2013/09/10::
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Not Your Typical Commute To Work: Flight to Canada Glacier, Antarctica
Not Your Typical Commute To Work: Flight to Canada Glacier, Antarctica
DATE: 2015/03/19::
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Gian Fulgoni Chairman & Co-founder, comScore (Festival of Media 2009) Part 2
Gian Fulgoni Chairman & Co-founder, comScore (Festival of Media 2009) Part 2
DATE: 2010/08/10::
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The best (scripted) wedding toast ever!
The best (scripted) wedding toast ever!
DATE: 2012/10/07::
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My Voyage from Migrant Farm Worker to Brain Surgeon
My Voyage from Migrant Farm Worker to Brain Surgeon
DATE: 2012/01/24::
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HydroPad Demo
HydroPad Demo
DATE: 2012/03/23::
22
Dr. Frank Wang calculates power generated by Hoover Dam
Dr. Frank Wang calculates power generated by Hoover Dam
DATE: 2011/07/19::
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HUMANITARIAN CRISIS ON THE SOUTH BORDER, KIDS CROSSING UP FROM GUATEMALA
HUMANITARIAN CRISIS ON THE SOUTH BORDER, KIDS CROSSING UP FROM GUATEMALA
DATE: 2014/06/12::
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MetaMo Training [Thai ver.] (5/6): BoE (Back of the Envelope)
MetaMo Training [Thai ver.] (5/6): BoE (Back of the Envelope)
DATE: 2014/07/06::
25
Heath Ceramics - Beautiful MUSA Tableware, Responsibly (extended version)
Heath Ceramics - Beautiful MUSA Tableware, Responsibly (extended version)
DATE: 2011/10/11::
26
Karl Johanson
Karl Johanson's Paper Starship
DATE: 2008/11/30::
27
Beyond the "Back of the Envelope"
Beyond the "Back of the Envelope"
DATE: 2014/03/05::
28
Estimating Ammonia Emissions from Livestock Using Low-Cost, Time-Averaged Concentration Measurements
Estimating Ammonia Emissions from Livestock Using Low-Cost, Time-Averaged Concentration Measurements
DATE: 2013/05/29::
29
Which five A1 companies pass Roger Montgomery
Which five A1 companies pass Roger Montgomery's cash flow test?
DATE: 2011/06/16::
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Clinton Supporters Ready To Take Fight To Convention
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buyMUSA: We Can Do This (:30)
buyMUSA: We Can Do This (:30)
DATE: 2011/09/21::
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Straight Up-Derivatives, Bailouts and YOU Part 1
Straight Up-Derivatives, Bailouts and YOU Part 1
DATE: 2009/01/29::
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buyMUSA: We Can Do This (:60)
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DATE: 2011/09/04::
34
Envelope Results in VisualAnalysis
Envelope Results in VisualAnalysis
DATE: 2012/02/10::
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Dr.ROWLEY explains RATIONAL behind PNM Commitment to RAPID RAIL sysyem!
Dr.ROWLEY explains RATIONAL behind PNM Commitment to RAPID RAIL sysyem!
DATE: 2012/10/05::
36
Heath Ceramics - Beautiful MUSA Tableware, Responsibly
Heath Ceramics - Beautiful MUSA Tableware, Responsibly
DATE: 2011/10/11::
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How does Roger Montgomery quickly calculate cash flow?
How does Roger Montgomery quickly calculate cash flow?
DATE: 2011/06/03::
38
AGI 2011: The Future of AGI Workshop Part 1 - Ethics of Advanced AGI
AGI 2011: The Future of AGI Workshop Part 1 - Ethics of Advanced AGI
DATE: 2011/08/31::
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John Heins & Whitney Tilson: "The Art of Value Investing"
John Heins & Whitney Tilson: "The Art of Value Investing"
DATE: 2014/12/10::
40
Basics of M&E in PPD, Section 5: Cost Benefits Analysis
Basics of M&E in PPD, Section 5: Cost Benefits Analysis
DATE: 2014/07/23::
41
cc TECH IN 2014 - Luis Von Ahn
cc TECH IN 2014 - Luis Von Ahn
DATE: 2014/12/02::
42
Graham Hancock - The War on Consciousness BANNED TED TALK
Graham Hancock - The War on Consciousness BANNED TED TALK
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Peter Norvig of Google on The History and Future of Technological Change
Peter Norvig of Google on The History and Future of Technological Change
DATE: 2012/02/21::
44
How to Calculate Price Elasticity of Demand (PED)
How to Calculate Price Elasticity of Demand (PED)
DATE: 2011/08/14::
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Image to 3D - NTB
Image to 3D - NTB
DATE: 2013/08/15::
46
Affordable Aluminium Foil Insulation Melbourne - In Stock Now!
Affordable Aluminium Foil Insulation Melbourne - In Stock Now!
DATE: 2010/12/12::
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Video #3: Third Party Certifications | Portland Home Builder, Legend Homes
Video #3: Third Party Certifications | Portland Home Builder, Legend Homes
DATE: 2013/01/14::
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Five Cost Saving Tips for Dimensional Weight Shipping with FedEx and UPS | Part 3
Five Cost Saving Tips for Dimensional Weight Shipping with FedEx and UPS | Part 3
DATE: 2014/10/10::
49
The fracking debate: Terry Engelder at TEDxPSU
The fracking debate: Terry Engelder at TEDxPSU
DATE: 2013/06/24::
50
How To Calculate the Monthly Cost of Renting Office Space for Lease (512) 861-0525
How To Calculate the Monthly Cost of Renting Office Space for Lease (512) 861-0525
DATE: 2012/06/07::
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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] In British English, a similar idiom 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]

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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