It's over 100000 paid customers, not paid users. E.g., your revenue number is way off... the article says their revenue for the quarter was $145 million. So I guess the average revenue per customer was approaching $1500 (well, unless I dropped a zero or three somewhere, which is possible). For Slack customers are organizations with potentially multiple users. Likewise, I think your 1:130 number is perhaps comparing apples to oranges.