Someone knocked on the door of the basement apartment on East 115th Street on March 13. A man let him in. A detective watched, and arrested the man who had opened the door.

In the man’s jacket, the police said, they found 38 pieces of paper. On them were jotted numbers, seemingly random hieroglyphics to the untrained eye.

But in truth they were far from random. To the police, each slip of paper was evidence of a crime, but they were also fragile relics of a bygone day in Harlem and New York City as a whole. These three-digit prayers were mementos from the old-school streets.

Each slip was a bet in a numbers racket.

Betting a number was once nearly as much a part of daily life in the city as shopping and working. The neighborhood numbers runner came around to collect and jot down the bets of housewives and dockworkers, businessmen and barflies. One could place a straight bet on a three-digit number or a combination bet that paid — albeit less — if the digits hit in any order.