https://sonyinteractive.com/en/our-company/business-data-sales/
Straight from Sony's website it has officially shipped/sold 1.537 billion units of software as of March 31, 2012. Where is this 1.24 billion coming from?
PS2 wasn't officially discontinued until December 2012/January 2013 hardware wise which means the hardware and software are both higher but we don't know how high.