From the Daily News:
It might not be a gold mine, but straphangers hanging onto almost-depleted MetroCards are sitting on a nice chunk of change.
More than a year ago, the MTA changed the formula for getting bonuses on pay-per-ride cards - making it more likely passengers will end up with a balance after they've taken their last trip.
And many riders don't know what to do with the leftovers. They won't make a turnstile spin, but they're not exactly worthless.
MetroCard math became difficult when the Metropolitan Transportation Authority's old easy-to-grasp, 20% bonus - buy five trips and get a sixth free - was reduced to 15% last year.
Buyers are ending up with odd amounts left on their cards - the MTA wouldn't estimate the total - and some apparently don't know how to ensure the money is spent.
To help the numerically challenged, Jim Schwartz, a market researcher who commutes from New Jersey, recruited two friends to compile the Transit Calculator/Spreadsheet. It shows what denominations to put on a card to wind up with a zero balance at the end: $4.50, $6.75, $15.65, $29.35, $31.30, $45, $60.65, $74.35 or $76.30.