Sports leagues, media outlets and more used to look down on betting as corrupting the supposed purity of athletics. But in 2018 the Supreme Court dealt a new hand, allowing all states to legalize betting. Now gambling is a fast-growing part of mainstream sports. Betting lines on games appear on ESPN’s own news ticker. Sports books are opening everywhere and phone-based apps keep evolving. But Las Vegas is still the nerve center of it all, and global sports correspondent Sam Borden takes us inside the Westgate sportsbook to see how the pros who make the odds find their perfect numbers.