> "If it books 80 percent through its restaurant partner sites, that means it charges 25 cents on about 2.4 million seated, and then charges $1 on the remaining 20 percent, or 600,000 seated, through its own site. So OpenTable is making $2.4 million a month...."

0.25 * 2.4 million + 1 * 0.6 million = $1.2 million /mo.

Still serious money, but off by a multiple of 2.