# Best way to generate random numbers at home? **URL:** \ **Category:** Factual Questions\ **Created:** [January 22, 2009, 6:21pm UTC](https://boards.straightdope.com/t/best-way-to-generate-random-numbers-at-home/482490 "2009-01-22T18:21:07Z")\ **Posts on this page:** 6\ **Page:** 2
**Author:** ![muttrox](https://avatars.discourse-cdn.com/v4/letter/m/a8b319/32.png) [@muttrox](https://boards.straightdope.com/u/muttrox)\ **Post date:** [January 22, 2009, 9:30pm UTC](https://boards.straightdope.com/t/best-way-to-generate-random-numbers-at-home/482490/21 "2009-01-22T21:30:09Z")
> [@Sapo](#): > > I am sorry I didn’t specify. No dice, no computers. I mean common daily objects in your grandma’s house. My grandma has dice and coins (and a calculator and a computer). Where are you drawing the line, I don’t understand your line. ---
**Author:** ![clairobscur](https://avatars.discourse-cdn.com/v4/letter/c/839c29/32.png) [@clairobscur](https://boards.straightdope.com/u/clairobscur)\ **Post date:** [January 22, 2009, 10:18pm UTC](https://boards.straightdope.com/t/best-way-to-generate-random-numbers-at-home/482490/22 "2009-01-22T22:18:46Z")
> [@Sapo](#): > > Is this really the best way to generate random numbers with stuff generally found at home and without resorting to making a mess, using higher math, etc? I used your prof’s method in a number of instances (I used to play RPG a lot). Except that I used the penultimate digit instead of the last one, since the last one being even or odd depends on the page you check (left or right). ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [January 22, 2009, 10:19pm UTC](https://boards.straightdope.com/t/best-way-to-generate-random-numbers-at-home/482490/23 "2009-01-22T22:19:25Z")
> [@Walton\_Firm](#): > > That’s a bad method. People are very bad at avoiding patterns. There are interesting experiments wherein people have been asked to type “as randomly as possible” on a keyboard – it turns out to be not very difficult to write a computer program which can predict, with surprising accuracy, which key they will hit before they hit it. Do you have a source for that? If so, we’d appreciate it [over here](http://boards.straightdope.com/sdmb/showthread.php?t=502972). ---
**Author:** ![Thudlow\_Boink](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thudlow_boink/32/320_2.png) [@Thudlow\_Boink](https://boards.straightdope.com/u/Thudlow_Boink)\ **Post date:** [January 23, 2009, 12:18am UTC](https://boards.straightdope.com/t/best-way-to-generate-random-numbers-at-home/482490/24 "2009-01-23T00:18:47Z")
> [@clairobscur](#): > > the last one being even or odd depends on the page you check (left or right). Yes, this is one major flaw in using the OP’s method exactly as described. I would think that using the last (or next-to-last) digit of “randomly chosen” phone numbers out of a phone book would be a better method than using “randomly chosen” page numbers—assuming that all ten digits are equally likely to appear as the last digit of a phone number, which seems reasonable but I don’t know for sure. [QUOTE=Sapo] For example, if you need a random number from 1 to 47, you open the first page, that is your last digit (units). Repeat for the next digit (tens). Here you can map 6-0 as 1-5 or discard them. If you got a 48, then start from the beginning. [/QUOTE] I don’t know what you mean by “map 6-0 as 1-5.” For your first digit, you could map 5-9 as 0-4 or discard them. For your second digit, you can’t do any such “mapping.” Even if you needed a random number from 1 to 44, it wouldn’t be fair to do such “mapping,” because then the numbers 40-44 would each have twice as many chances to appear as any of the others. ---
**Author:** ![Indistinguishable](https://avatars.discourse-cdn.com/v4/letter/i/90ced4/32.png) [@Indistinguishable](https://boards.straightdope.com/u/Indistinguishable)\ **Post date:** [January 23, 2009, 12:29am UTC](https://boards.straightdope.com/t/best-way-to-generate-random-numbers-at-home/482490/25 "2009-01-23T00:29:22Z")
> [@muttrox](#): > > Look at the second hand of a clock. Divide the 60 seconds into equal segments, and see what you get. That gets you 2,3,4,6,12,15,20, or 30 choices. For generation of just a few random bits, this idea seems the best to me. The only problem is, if you want to generate more random digits, you really can’t do so immediately; human bias as to how long to wait before re-looking will creep in, at a level significant in terms of quantizing the result into seconds. How to solve this problem? Perhaps get a stopwatch with the ability to spit out time at an interval so fine-grained that you couldn’t possibly expect human bias to matter so far as the least-significant digit goes. ---
**Author:** ![Sapo](https://avatars.discourse-cdn.com/v4/letter/s/ec9cab/32.png) [@Sapo](https://boards.straightdope.com/u/Sapo)\ **Post date:** [January 23, 2009, 12:52am UTC](https://boards.straightdope.com/t/best-way-to-generate-random-numbers-at-home/482490/26 "2009-01-23T00:52:59Z")
> [@Thudlow\_Boink](#): > > Yes, this is one major flaw in using the OP’s method exactly as described. Come to think of it, you are right. I may be misremembering. This was years ago. Second to last number might have been it. > [@](#): > > I would think that using the last (or next-to-last) digit of “randomly chosen” phone numbers out of a phone book would be a better method than using “randomly chosen” page numbers—assuming that all ten digits are equally likely to appear as the last digit of a phone number, which seems reasonable but I don’t know for sure. This is a big assumption that I am not sure I am comfortable making. It would be great if someone in the telco industry had an answer. This might merit its own thread. The stopwatch method I have used. Hundredths of a second is all it takes (at least for my slow reaction times) to be close enough to random. [Previous page](https://boards.straightdope.com/t/best-way-to-generate-random-numbers-at-home/482490.md?page=1)