Should you find yourself in Manhattan without a working iPhone and in need of some directions, don't forget about this old trick. A Redditor revived it today, posting this photo and asking, "What is this sorcery?"

NYC Tourist explains it with this below example, saying, "If you have the avenue address number for your particular destination, there's a simple chart to help you locate which NYC street your destination is closest to." Well, sort of simple... you probably want to put a copy in your wallet!

Take the address. (Example: Guggenheim Museum, 1071 Fifth Ave)
Drop the last Figure. (Guggenheim Museum, 107)
Use the chart below to determine what to do next. (For the Guggenheim, the Manhattan Address Chart Locator tells you to subtract 18 from 107, the number you got from step two.)
The Guggenheim Museum is closest to 89th Street. (107-18=89)

But the fun doesn't stop there—did you also know that the numbers on the lamposts in Central Park are cross street indicators? If a lamppost is numbered 7304, it is located between 73rd and 74th streets. "The '4' designates that the post is the fourth post in from Fifth Avenue. In the upper reaches of the park, where street numbers are 100 and higher, the '1' is omitted; for example, a post numbered 0500 is between 105th and 106th."

And if you have trouble between your North and your South... another Redditor has pointed to the "N O S E" system. North = Odd and South = Even, so buildings with an odd address are on the north side of the street, and those with an even address are on the south side. Though this only works west of Fifth Avenue. What other tips are hidden out there?