All projected numbers appear in red. There are 110 election authorities in the State of Illinois, 102 county authorities and 8 local municipal authorities (Rockford, Chicago, Aurora, Bloomington, Peoria, Galesburg, Danville and East St. Louis). For each of these 110 different local election blocks I simply apply the current vote ratio and extrapolate those numbers as if 100% of that area's precincts had reported.
For example, if in one area 5 out of 10 precents have reported and Candidate A had 100 votes and Candidate B has 80 votes the extrapolated Projected totals would be that Candidate A is projected to receive 200 votes and Candidate B is projected to recieve 160 votes in that area. Do that for all 110 election authorities and add up the results to get the projected totals.
It's a very simple projection formula and it performs poorly very early in the night when only a few precincts have reported. It obviously gets better with more data. When it is early in the night and many or most election authorities haven't yet reported any data it can show some really weird projections so just be patient.