The easiest way to work out what 100 days for this past Wednesday is would be to take a look at how many weeks is in the next 100 days.
If we know that a week is 7 days, and every 7-day cycle brings us back to Wednesday again how many 7 day cycles go into 100?
Simply divide: 100/7= around 14.28
So 14 7-day cycles (or 98 days, just multiple 14*7) is the closest we can get by counting in weeks.
If in 98 days it will be Wednesday again, we can easily count to more days: Thursday, Friday... And we are on 100!
So the answer you are looking for is Friday.
