if there are 3718 MR refractors out of a million cards I think the odds would be 1:268. But on a side note there are 11 potential MR refractors but only 5 have been discovered. To date no refractors or holofoils have been found for MR3, MR4A, MR6, MR6A, MR7A, and MR8. So either these cards were dispersed into later boxes or weren't made at all. If only 5 MR refractors exist odds would be more like 1:645 I believe
1:268 sounds like odds per card. (My math comes to 1:274) Divide by 5 to get odds per pack: 1:55
1:124 odds would equal only 1625 MR so those have to be how many HFs (‘refractors’) there are, not the 3718 MR GRs.
So there should be ~147 HF of each MR vs 338 GR of each MR