# Square roots

**URL:** <https://boards.straightdope.com/t/square-roots/4917>\
**Category:** Factual Questions\
**Created:** [November 24, 1999, 7:26pm UTC](https://boards.straightdope.com/t/square-roots/4917 "1999-11-24T19:26:00Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Greg\_Charles](https://avatars.discourse-cdn.com/v4/letter/g/839c29/32.png) [@Greg\_Charles](https://boards.straightdope.com/u/Greg_Charles)\
**Post date:** [November 24, 1999, 7:26pm UTC](https://boards.straightdope.com/t/square-roots/4917/1 "1999-11-24T19:26:00Z")

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How do you calculate a square root without a calculator? I know there is some method based on iterations and the Taylor series. Someone told me about a method that resembles long division and doesn’t require iterations, but he can’t remember how it works.

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**Author:** ![Boris\_B](https://avatars.discourse-cdn.com/v4/letter/b/fbc32d/32.png) [@Boris\_B](https://boards.straightdope.com/u/Boris_B)\
**Post date:** [November 24, 1999, 7:37pm UTC](https://boards.straightdope.com/t/square-roots/4917/2 "1999-11-24T19:37:00Z")

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The only way I know is to do the iterations … divide the number by a smaller number, and keep adjusting your divisor until it equals (or nearly equals) the quotient. It shouldn’t take too long to get a few decimal’s worth of accuracy.

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**Author:** ![Arnold\_Winkelried](https://avatars.discourse-cdn.com/v4/letter/a/3d9bf3/32.png) [@Arnold\_Winkelried](https://boards.straightdope.com/u/Arnold_Winkelried)\
**Post date:** [November 24, 1999, 7:40pm UTC](https://boards.straightdope.com/t/square-roots/4917/3 "1999-11-24T19:40:00Z")

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I learned [this method](http://www.math.uio.no/~einara/sqrt.html) in grade school. I was going to retype it in, but fortunately found an explanation on the web.

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La franchise ne consiste pas à dire tout ce que l’on pense, mais à penser tout ce que l’on dit.  
H. de Livry

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**Author:** ![Keeves](https://avatars.discourse-cdn.com/v4/letter/k/f05b48/32.png) [@Keeves](https://boards.straightdope.com/u/Keeves)\
**Post date:** [November 24, 1999, 8:24pm UTC](https://boards.straightdope.com/t/square-roots/4917/4 "1999-11-24T20:24:00Z")

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Cool! I had learned that in school too, but forgot how. Thanks!