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Massachusetts Institute of Technology

Street-Fighting Math

Massachusetts Institute of Technology via edX

This course may be unavailable.


Too much mathematical rigor teaches rigor mortis: the fear of making an unjustified leap even when it lands on a correct result. Instead of paralysis, have courage: Shoot first and ask questions later. Although unwise as public policy, it is a valuable problem-solving philosophy and the theme of this course: how to guess answers without a proof or an exact calculation, in order to develop insight.

You will learn this skill by mastering six reasoning tools---dimensional analysis, easy cases, lumping, pictorial reasoning, taking out the big part, and analogy. The applications will include mental calculation, estimating population growth rates, understanding drag without differential equations, singing musical intervals to estimate logarithms, approximating integrals, summing infinite series, and turning differential equations into algebra.

Your learning will be supported by regular readings that you discuss with other students, by short tablet videos, by quick problems to help you check your understanding, by weekly homework problems, review and and a final exam. You will work hard, and, by the end of the course, have learned a rough-and-ready approach to using mathematics to understand the world.

All required readings are available within the courseware, courtesy of The MIT Press. A print version of the course textbook, Street-Fighting Math, is also available for purchase. The MIT Press is offering enrolled students a special 30% discount on books ordered directly through the publisher’s website. To take advantage of this offer, please use promotion code SFM30 at The MIT Press.


  • Do I need to buy a textbook?
    • Back in 2010, MIT Press agreed to publish the textbook, Street-Fighting Mathematics, under a free license (in print and online).
    • Thus, the book is legally available all over the internet, including on this course platform.
    • As a registered student in this course, you can also purchase a printed book from MIT Press at a discount.
  • Do you often get into street fights?
    • The last time was in high school, when I was attacked for being “different” and suspended for fighting back.
    • However, in my problem-solving fights (and now that I’m older!), I regularly use reasoning tools and we’ll do the same in this course.

Taught by

Sanjoy Mahajan and Isaac Chuang


4.0 rating, based on 7 Class Central reviews

Start your review of Street-Fighting Math

  • Anonymous
    This course deals with an important topic that is neglected in the traditional mathematics curriculum: how to guess and estimate the answers to math problems. You will learn, for example, how to estimate the size of the diaper market in the United S…
  • It's a good course, but it's a pity we don't have access to all the features of the mooc. It is not really self-paced.
  • Okayama Brett
    You'll learn some techniques for approximating solutions to mathematical problems. I'd never seen those techniques before, and they give insight into how a mathematical mind can attack difficult problems. The course is based on the professor's book.

    Some of the problems posed were hard and relied on some intuition, and at times I felt the professor assumed we knew some math tricks which would make some of the problems straightforward, but I didn't know them so I was struggling.

    Overall though I'd recommend the course, even as an archived course. It's worth seeing the techniques so you can apply them in the future in other courses.
  • Anonymous
    I have mixed feelings about this course. Some of the topics seemed so basic as to be almost common sense. Others were quite challenging and presented in a way that didn't always make them understandable.

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