This road sign is located along AZ Hwy-89A ten miles north of Congress, Arizona.

The road sign says...

+-----------------+ | Congress 10 | | Jct SR 71 10 | | Wickenburg 25 | +-----------------+the numbers are: 10 71 10 25 the off-by-one math is: (71 - sqrt(25)) / (10 + 10 + 1) observe... sqrt(25) = 5 71 - 5 = 66 10 + 10 = 20 66 / 21 approximates Pi (3.14) off-by-one: 20 is 1 less than 21 66 / 20 is 3.3 3.3 is 5.1% higher than 3.14## Update::2006.09.24

RoadHacker drove past this road sign again on 22 September 2006. A re-examination of the numbers resulted in another off-by-one find.

the numbers are: 10 10 25 71 the off-by-one math is: sqrt(sqrt(71 + 10)) = (10 / sqrt(25)) + 1 observe... 71 + 10 = 81 sqrt(81) = 9 sqrt(9) = 3 sqrt(25) = 5 10 / 5 = 2## Update::2007.11.26

The

spffunction was added to the BARS toolbox on 26 November 2007. Thespfcalculates the sum of the prime factors for a composite number.the numbers are: 10 10 25 71 the math is: sqrt(25) + spf(spf(sqrt(71 - spf(10)))) = 10 observe... spf(10) = 7 [prime factors for 10: 2, 5] 71 - 7 = 64 sqrt(64) = 8 spf(8) = 6 [prime factors for 8: 2, 2, 2] spf(6) = 5 [prime factors for 6: 2, 3] sqrt(25) = 5 5 + 5 = 10

**Creator:** Gerald D. Thurman
[gthurman@gmail.com]

**Created:** 28 May 2006

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