Josua H (14 Sep 2025)
"How I found the 153° on the clock"


 

Dear Doves

I'd like to share with you how it happened that I found that on an analogue clock, the angle between the hour-dial and the minute-dial is 153°.

It was during our family summer vacation, where I just arrived together with my family at our holiday destination, a village name FIESCH. The origin of that name comes from the latin vīcu(s) and simply means "Village". However, in retrospect I can't un-see the FISH in this word..!

After unpacking our suitcases, I saw that there was a big analogue clock on the wall. Unfortunately, it seemed not working (batteries empty?). I somehow kept staring at the clock. At the same time, I was thinking about the calculation 9x17 = 153, and at that moment I suddenly asked myself:
what is the angle between the dials at time 9:17? How cool would it be if it was exactly 153°?

So at the first possible moment, I separated myself from my family with a pen and a piece of paper and I started my calculations with the time 9:17, and I figured out that it is not a match for 153°, but it is relatively close.

Actually, in my first attempt to calculate it, I made an error in my calculation, and I ended up with 234/11 for the seconds. The 234 intrigued me, because it reminded me of "Vincent Tans" number 2.34 (just search FiveDoves for Vincent Tan!). It made me think a lot about 234 because it reminded me of "23. or 24. September". -> see https://www.fivedoves.com/letters/aug2025/josua831-1.htm

Later that evening, I continued researching all possible solutions, using Grok. Even Grok made some wrong attempts in the beginning and I had to "educate" it on how to calculate all possible solutions. And only when it suddenly spit out 21:11 as a solution, I realized how perfectly it relates to John 21:11! So you see, it was not my math skills, it was simply a gift from above to "discover" this, at the right time. All glory to God!

However, at least I want to share now how to calculate the exact time at 21:11:xx, for those who are interested (and as proof that Grok did not fool us! :-)).

- In 12h, the hour-dial moves 360°. Consequently, it moves 30° per hour. Consequently, it moves 0.5° = 1/2° per minute.
- In 1h, the minute-dial moves 360°. Consequently, it moves 6° per minute.
- At 21:11, the hour-dial is at 9x30° + 11*0.5° = 275.5°
- At 21:11, the minute-dial is at 11x6° = 66°
- As we start the angle at 12 o clock, it is easier to use the "other angle" between the dials: 360°-153° = 207°
- 275.5° - 66° = 209.5°. -> 360°-209.5° = 150.5°. That's close to 153°, but still 2.5° off. 2.5° is a bit less than half a minute. So it means that 21:11 actually is a valid solution, and about half a minute later it will be exactly 153°.
- How many seconds are left until the angle will be exactly 153°?
- The hour-dial moves 0.5°/60 = 1/120° per second.
- The minute-dial moves 6°/60 = 1/10° per second.

With that, we can finally write:

HourDial -MinuteDial -HourDialMovement +MinuteDialMovement = 207°

(note that the HourDialMovements decreases the angle, while the MinuteDialMovement increases the angle. That's why we must subtract the HourDialMovement)

-> 275.5 -66 -x/120 +x/10 = 207
-> 209.5 -x/120 +12x/120 = 207
-> 209.5 -11x/120 = 207
-> 209.5 -207 = 11x/120
-> 2.5 = 11x/120
-> 2.5*120 = 11x
-> 300/11 = x
-> x = 27.272727 (= 27 + 3/11) seconds

So the exact solution is indeed 21:11 with a rest of 27.27272727 seconds.

q.e.d.

Maranatha! YbiC, Josua
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You're LED by PALMONI, Josua!
John