This is very hard. It took me several attempts, the final one taking 4 hours. My solve took three steps. One: find options for each set of modular numbers. I gave each of 147, 258 and 369 different colours. Then, established which colour each cell could be. For the two number sets, 258 and 147, there was an option. So, one set became numbers in the corners, the other in the middle. Then, I chose one number set and went until it failed. That established which colour was which modular set. From that point it was very, very simple.
This was hard. Because the video was not in English, I had to really figure out how to do this type of coloring puzzle. Merci!
This is very hard. It took me several attempts, the final one taking 4 hours. My solve took three steps. One: find options for each set of modular numbers. I gave each of 147, 258 and 369 different colours. Then, established which colour each cell could be. For the two number sets, 258 and 147, there was an option. So, one set became numbers in the corners, the other in the middle. Then, I chose one number set and went until it failed. That established which colour was which modular set. From that point it was very, very simple.
One can solve it logically from start to finish, as I did. At 10:30, the disambigation between 147 & 258 is around b6, with the 2 white dots