The MTA has raked in millions thanks to leftover MetroCard cash, and though those funds have been solidly put to use fumigating potentially bedbug-infested subway cars, it's frustrating for the rest of us to get tripped up by leftover dollars and nickels. The $2.45 left on a standard $19.95 card could have gotten you a quarter of a latte in Greenpoint! And sure, you could just put another $19.95 on that card, but even that will leave you with a useless $2.40 at the end, and that vicious cycle will continue all over again, until you finally become so frustrated you toss your card onto the subway tracks and a nice rat takes it home to use as a blackout curtain. What's a straphanger to do?

Thankfully, I Quant NY has come up with a clever life hack to keep the MTA from getting their grubby little hands on your money. Though the agency appears to PURPOSEFULLY TRICK YOU into ceding your small change to them by casually offering non-round numbers up front—$9.45, $19.45 and $40.95. At first glance, these numbers seem harmless enough, but all of them will trap dollars and/or cents on your card after one round.

You have the option of choosing other amounts that haven't been dictated to you by the MTA overlords, of course, but that requires math, and math is hard and terrible. I Quant NY crunched the numbers for the rest of us, and discovered the magic card amounts: $9.55, $19.05 and $38.10. The first amount will leave your card with 3 cents leftover after 4 rides, a mere pittance! The third tops out at 16 rides with 1 cent leftover, and you'd probably drop that penny at the turnstile anyway. And $19.05—the "magic number," as I Quant NY purports—empties the card completely after 8 rides.

This isn't the first time someone's come up with a handy tool for measuring out MetroCard funds, of course. After the MTA hiked up fares last year, a website published the NYC MetroCard Calculator, allowing you to clock in various amounts to figure out how much money you'll have left on the card. There are also a few apps available to help you keep your cash out of the MTA coffers. And since those pay-per-ride cards are for tourists, anyway, for an even more satisfactory way to best the MTA, either purchase an unlimited monthly card—perfect for regular subway those who appreciate being able to take the subway 6 times in one day just to cheat the agency out of $15—or screw the MetroCard altogether and get a bike.