Multi-Moon Calendar Math Help

So I am just adapting this calendar of Faerun for use in Tellene (the world of hackmaster). Which has 3 moons, a 28 day cycle. 34 day cycle and an 80 day cycle in a 364 day calendar. I am just trying to figure out what this person did for the moon cycles (the code in question is 437-472 if you look at the github)&nbsp; <a href="https://github.com/Ciorstaidh/Roll20-API/blob/master/Faerun%20Calendar%20v2.4" rel="nofollow">https://github.com/Ciorstaidh/Roll20-API/blob/master/Faerun%20Calendar%20v2.4</a> The lines in question that I am referring to is this section.&nbsp; &nbsp; &nbsp; getmoonV = function() { &nbsp; &nbsp; &nbsp; &nbsp; var ordinal = state.Calendar.now.ordinal; &nbsp; &nbsp; &nbsp; &nbsp; var moonNo; &nbsp; &nbsp; &nbsp; &nbsp; var moon; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; moonNo = Math.ceil(ordinal/3)-Math.floor(Math.ceil(ordinal/3)/8)*8; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; switch(moonNo) { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; case 1: &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; moon = 'First Quarter'; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; break; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; case 2: &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; moon = 'Waxing Cresent'; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; break; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; case 3: &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; moon = 'New'; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; break; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; case 4: &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; moon = 'Waning Cresent'; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; break; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; case 5: &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; moon = 'Third Quarter'; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; break; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; case 6: &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; moon = 'Waning Gibbous'; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; break; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; case 7: &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; moon = 'Full'; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; break; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; case 0: &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; moon = 'Waxing Gibbous'; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; break; &nbsp; &nbsp; &nbsp; &nbsp; } &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; return moon; &nbsp; &nbsp; }, So the question for me is how is moonNo calculated? I get dividing by 8 to get the 8 cases, but why is ordinal being divided by 3?&nbsp; Ordinal is the count of days from the 1st day of the year, and I know the moon of Faerun has a 30 day cycle.&nbsp;

That is set up to give the moon a 24 day cycle, it stays on each phase for 3 days.

You have a problem with your world's 3 moons. Two of them dont divide into the year perfectly, so you'd need to track the phases over multiple years and IIRC you cant do that with that script.

Thanks GiGs