We almost found a golden ratio roadsign in Tempe.

The "golden ratio" approximates the value

`1.618`

.[no picture] the sign said: +------------------+ | Jct 101 2 | | Mesa 5 | | Apache Jct 23 | +------------------+ the numbers are: 101, 2, 5, 23 the math is: (101 / (5 - 2)) / 23 101 / 3 = 37 37 / 23 = 1.6086 1.6086 is 1.61 rounded to nearest hundredth phi is 1.6180, which rounded to nearest hundredth is 1.62 1.6180 - 1.6086 = 0.0094 1.6180 is 0.58% larger than 1.6086The road sign is on eastbound US Hwy-60 (Superstition freeway) just east of the I-10 interchange.

## Update::2006.04.03::Not Quite e -- Off By 0.01

The sign used in this BAB was re-examined for Road Sign evaluation and we almost discovered the value for

`e`

.summation(2, 5) = 2 + 3 + 4 + 5 = 14 101 / (23 + 14) = 101 / 37 = 2.72972972 e is 2.71828183 rounded to the nearest hundredth e is 2.72 versus our result of 2.73 (off by 0.01)## Update::2006.04.11

I was reading about how RoadSignMath.com does scoring and they have a "prime sign type." The 3rd edition rules state these signs "must contain at least three numbers, and all numbers on the sign must be prime numbers and must be greater than 10."

The sign used in the BAB contains four numbers and all of them are prime (

`101, 2, 5, 23`

), but it is not valid RSM because two of the numbers are less than 10.

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

**Created:** 25 February 2006

This work is licensed under a Creative Commons License.