Lancashire 418 (Bohannon, Livingstone 71, Vilas 51) beat Derbyshire 244 (Godleman 111, Gleeson 5-64) and 129 (Bailey 3-14) by an innings and 45 runs
While it might take a mathematical genius to work out the exact equation needed, it was reckoned to be around five past five when Glamorgan were bowled out at New Road that Lancashire knew they would be returning to county cricket's top-flight.
Ifs, buts and maybes still remained however, and it was not until the unfortunate figure of an injured Ravi Rampaul walked out to bat in the swirling rain and proceeded to hit Matt Parkinson straight up in the air that promotion could properly be celebrated.
That the Red Rose have regained their Division One status with two games to spare will doubtless come as a relief to those supporters so used to final day arithmetic, but it is no less than Lancashire deserve, after an unbeaten season which has seen them ruthlessly put away opponents in much the same way as Derbyshire were ground down on this third day.
It was not all bad for the visitors who actually enjoyed a profitable morning session, taking four wickets as Lancashire progressed to 365 for 6 and a first innings lead of 121.
This came after their disheartened bowlers took just a single wicket on day two, but once Derbyshire grabbed the new ball they immediately profited, with Liam Livingstone only managing to add one run to his overnight score before he edged a rising delivery from Rampaul to wicket keeper Harvey Hosein for 71.
Livingstone's dismissal broke a third wicket partnership of 199 with Josh Bohannon, but he was quickly followed back to the dressing room by Glen Maxwell who was out first ball, playing on to Rampaul in what is the Australian's final appearance of the season for the county.
Bohannon's long vigil finally ended soon after when he edged to Wayne Madsen at first slip off Fynn Hudson-Prentice for a brilliant debut first class century, with his total of 174, including 23 fours and two sixes. He is just one of Lancashire's young players who could prosper at the higher level.
Rob Jones and Lancashire skipper Dane Vilas proceeded to build a partnership of 67 for the sixth wicket, with the South African reaching 1,000 runs for the season and bringing up his own half-century, before he nicked behind off Anuj Dal on the stroke of lunch.
Resuming on 365 for 6 after lunch the hosts immediately looked to add quick runs and Tom Bailey had progressed nicely to 26 when he was run out attempting a quick single by a direct throw from Dal who then clean bowled Jones for 37.
Parkinson was trapped in front by Matt Critchley for one before Dal, who finished with figures of 3 for 60, did the same to Saqib Mahmood as Lancashire were bowled out for 418.
Under darkening Manchester skies, Bailey then got the early breakthrough when he enticed Luis Reece to drive at a wide one and play on to his stumps for six.
Bailey followed up with the prize wicket of first innings century maker Billy Godleman who was lbw for 10 to leave Derbyshire 49 for 2 at tea with Wayne Madsen and Leus Du Plooy set to negotiate a tricky evening session.
It always looked a big ask for a side with little to play for and with one eye on their forthcoming appearance at the T20 Blast finals day and perhaps unsurprisingly a trickle became a torrent when Madsen edged Bailey to Livingstone at slip before spin took over and Maxwell accounted for Du Plooy the same way.
Critchley became Parkinson's first victim, trapped in front for 1, with Alex Hughes next to go, brilliantly caught by Richard Gleeson at backward square leg for 33 off Maxwell.
It was all over bar the shouting and Derbyshire meekly rolled over, losing their last three wickets for no runs in 11 balls as Fynn Hudson-Prentice was run out, Dal was stumped and Rampaul skied one off Parkinson, who finished with 3 for 28, to seal the deal.
Cue the celebrations and a victory march which should see Lancashire claim the Division Two title with just five points needed over the next two games. Put away that abacus.