Challenge #241: Friday the 13th

[euanwilson]

Spoiler

I had to borrow an idea from another user about reading in the start and end date using the text input but once that was out the way this one wasn't so bad. 

After generating a comprehensive list of dates between the start and end date it was a case of using formulas and filters to get a list of the Friday 13ths. Finally the summarize tool was used to group each instance of the date by year. 

[carmenrapariz]

Spoiler

[Jonny]

My Solution:

Spoiler

 

Bonus:

I re-run the workflow for a thousand years from 1500 until 2500 and there has been/will be NO single year without at least a Friday 13th. Notwithstanding any statistics calculation, data is telling me there will always be one!

[Elias_Nordlinder]

My solution, fun to work a bit with generate rows.

Spoiler

[nravik]

Took inspiration from @JennyMartin idea. Thank you!

Spoiler

!!

[ncrlelia]

Challenge 241

[danilang]

Freaky Friday.  And no, there are no years without Friday the 13th.  See the spoiler for details on the proof

Spoiler

For the proof.  There are only 14 possible unique calendars.  There are 7 that have Jan 01 on each day of the week.  For each of these you can have either a leap or non-leap year.   Find all 14 and check that they have Friday the 13th in them

Dan

[Erin]

Spoiler

I really wanted to do this with a generate rows that would add on a date - but couldn't figure out how to do that. I wonder if it is even possible. I ended up generating rows for month and year like the posted solution did, but need more experience with date formulas.

[JoePC]

Solution Attached

[aluthra]

Spoiler

Friday the 13th - solved