We tend to get a bit lazy during summer, so I'm going to keep my brain sharp by combining work with a few mental exercises.

Let's see: okay, the archly significant progressive rock band Yes will play Friday in the Grand Theater at Foxwoods. It's the band's 50th anniversary, so if we quickly add up the ages of the current band members — sole founding dude/guitarist Steve Howe, drummer Alan White, vocalist Jon Davison, keyboardist Geoff Downes and bassist Billy Sherwood — we get 305 years!

Of course, this edition of Yes is only one of two versions of Yes currently out on a half-centennial tour. The other, being billed as The Quintessential Yes Featuring (sole founding dude/vocalist Jon) Anderson, (keyboardist Rick) Wakeman and (guitarist Trevor) Rabin, will hit the western U.S. later this summer.

Someone's not getting along!

Anyway, the latter version also features bassist Lee Pomeroy and drummer Louis Molino III. Since I can't find Molino III's age, a quick bit of addition shows the combined ages of the other four is 267 — meaning Molino III, who is without a doubt the least well-known of any of these people — needs to be 55 for the Quintessential Yes to be older than the Yes playing Foxwoods.

Why is this important? Because I did all that cypherin' in my head without any calculators or techno-gimmickry, meaning I've still got those math-y chops even though I'm old enough to be in both Yesses! You know who else still has math-y chops? All 600-plus years of both Yesses. That's some hard music!

Fortunately, it still sounds great. At Foxwoods, expect "Perpetual Change," "Close to the Edge," "Roundabout," "Soon," "Yours is No Disgrace" and "Starship Trooper" — and since Wakeman's in the other band, you won't have to watch an old man wearing a sparkly cape.

Yes, 8 p.m. Friday, Foxwoods' Grand Theater; $25, $40; 1-800-200-2882.