The disco ball was turning. It would complete its revolution in 43.247 seconds. Just now, 100 times since he'd arrived. It had 1579 mirrored faces. That was a good number. Prime and a Fibonacci. Doubly good. Three tiny squares of mirrored glass were missing, showing the grey of the adhesive beneath. 

"39.7617907."

"What? Oh, square roots again." 

His brother smiled a sigh, then leaned nearer to combat the thunderous bass and the high pitched chatter. It wasn't enough. He had to shout over the music.

"I'm nearly done. Just a few more minutes, ok?"

He took the shrug as acceptance and headed back towards the toilet, one or two clients in tow. He would be gone at least half an hour. Dimly his voice carried, laughing conspiratorially:

"He's ok. He's just on the spectrum. He's 'special' you know."

The place stank of sweat. The noise assaulted him on all levels. So, he stared at the ball, spinning and certain and constant. It had completed 3 more revolutions. Lasers had been added to the previous light show. The ball too was on the spectrum. He liked that.