Math is painful.

CIAC football playoff math can make one’s brain ooze out of one’s nose.

‘Tis the final week of the Connecticut high school football season. The playoffs start next week with 32 teams throwing down to earn a state title across four divisions.

Twenty-one teams have unofficially qualified — nothing is official until the CIAC football committee rubber-stamps the rankings the day after the end of the regular season which, if weather forecasts are correct, may not be for a while.

That leaves 11 berths available so, as a public service, here’s a primer that hopefully clears everything things up:

CLASS LL

IN: Three-time defending champion Darien (9-0), Greenwich (9-0), New Britain (9-1), Newtown (9-0), Shelton (9-0) and New Britain (9-1).

Darien, Shelton and Newtown have the best chances to host a home quarterfinal next Tuesday with wins. If both Greenwich and Southington win, they will be in a tight race for the fourth seed.

Fairfield Prep (vs. West Haven) is in with a win on Thanksgiving. It can also qualify with a loss, but more on that in a moment.

New Canaan (7-2) and Staples (7-2) can qualify with Thanksgiving wins. There are a few problems, though. The first is that New Canaan plays Darien, the top-ranked team in The Day's state poll. The second is that Staples plays at Greenwich, ranked second in the poll. The third is that both can win and still be out-pointed by Prep, even if it loses, depending on bonus points.

A team receives 10 bonus points for every win by a team it beat.

East Hartford is currently behind Prep, New Canaan and Staples in the rankings, but may be in better shape than the latter two. It hosts Manchester (4-5) on Wednesday and needs a win, combined with a loss by either New Canaan or Staples.

CLASS L

IN: Naugatuck (9-0), Middletown (9-0), Hand (9-0) and Maloney (8-1). All but Maloney have clinched a home quarterfinal, and Maloney will get the final home game with a win over Platt.

Bunnell (vs. Stratford), Windsor (vs. Middletown), North Haven (vs. Amity), and Platt (vs. Maloney) all qualify with wins.

RHAM needs to beat Bacon Academy (3-6) on Wednesday and, preferably, have either Windsor, North Haven or Platt lose.

Wethersfield needs to beat Newington (3-6) and have Platt and RHAM lose. Guilford is mathematically alive, but plays at nemesis Hand on Wednesday.

CLASS M

That’s ‘M’ as in ‘Messy.’

IN: St. Joseph (8-1), Sheehan (8-1), Berlin (9-1), Killingly (9-1) and Cheney Tech (8-2). The first four have clinched home quarterfinals.

Brookfield (vs. one-win Bethel) and East Haven (vs. Branford) qualify with a win.

Things then get messy.

Abbott Tech/Immaculate (6-3) is presently ranked eighth but will get few points from beating winless MCW United on Thursday. The same applies for No. 9 Rockville (6-3) against one-win Ellington on Wednesday. Ditto No. 11 Law (6-3) against one-win Foran (1-8) on Thanksgiving.

No. 10 Wolcott (6-3) qualifies with a win over Holy Cross (6-3) on Thanksgiving.

No. 12 Weston (6-3) needs to beat Barlow and hope for a miracle. No. 13 Branford (5-4) needs more than that.

CLASS S

IN: Bullard-Havens (10-0), Ansonia (9-0), Stafford/East Windsor/Somers (9-0), Cromwell/Portland (9-0), Bloomfield (8-1) and Woodland (8-1).

B-H and Ansonia have clinched home quarterfinals. S/EW/S (vs. Windsor Locks/Suffield/East Granby) and Bloomfield (vs. Glastonbury) will clinch the other home quarters with a win.

Tuesday's No. 7 Haddam-Killingworth (8-1) at No. 9 Valley Regional/Old Lyme (7-1) game in the equivalent of a Class S qualifier.

H-K won’t be cooked if it loses, though. Valley/Old Lyme will.

No. 8 Plainfield qualifies with a win over Griswold (5-4) on Thanksgiving.

Now it gets fun — No. 11 Seymour (6-3) has a longshot chance if it beats Woodland on Wednesday, and if Plainfield loses.

H-K will likely outpoint Plainfield if they both lose, and Seymour if it wins.

You may now grab some aspirin and seltzer.

n.griffen@theday.com