And maybe it was just Matt's hangover, but DHH never said "500 x $40 = $125,000." The slide actually says 400 customers @ $40/mo = $200,000/year, as you can see in the video (http://omnisio.com/startupschool08/david-heinemeier-hansson-... @ 11:50)

Matt was referring to one of the slides toward the end (23:49).

My guess is there was some length of time assumption that he just glossed over. 500 x $40 x 6.25 months = $125,000 for instance.

He said per month in his speech. And why would he choose 6.25 (or even 6) as his length of time?

Oh I remember the mental disconnect I had when he said that, I'm just saying that I assume he misspoke and that slide was supposed to have a real meaning of some sort over time. It seems much more likely that he thought through the slide when he made it and just blundered when on the spot than the other way around.

I also had a moment of confusion on the slide that said 400 x $40 = $200k until I realized he was talking about 12 months and rounding. I imagine something similar was happening here.

I would agree, except everything else was 1 month or a year, and this would have been 6ish months. Kind of random, and doesn't make sense in context. Also, why round from $120 to $125.

If he had said $250k I'd chalk it up to rounding for a year and accidentally saying a month.

Well 125,000 in base 11.5 number system is pretty close to 250,000 in base 10.

...

Yeah, that's all I got.

Lol.

Yes. Where he was talking about scaling.

yes, i don't recall the math mistake either