In these uncertain financial times, one thing remains certain — the ever-expanding national debt. But it's growing at such an accelerated rate, the clock that has kept track of the deficit since 1989 has had to add a digit.

The National Debt Clock switched its digital dollar sign to a 1 on Monday to accommodate the nation's ballooning deficit, now past the $10 trillion mark, thanks to Congress' $700 billion bank stimulus package.

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Few passersby looked up at the billboard Wednesday afternoon, as the clock tallied each American family's share of the debt at just past the $86,000 mark. But one man on a cell phone stopped to tell the person on the other end just how much they owed.

Real-estate developer Seymour Durst first began publicly clocking the nation's deficit in 1989, erecting the digital billboard a block from Times Square.

"Early in the 1980s, he recognized that the national debt was a problem and was going to be a burden for his children and grandchildren and the next generation of Americans," said Jordan Barowitz, a spokesman for the Durst Organization, which owns the clock. "So he put it up to call attention to the problem that we can’t borrow our way out of bad times."

Over the years, the debt has grown, and so have the zeroes on the clock, though it was turned off for a time in 2000.

"It shut off for a few years during the Clinton administration, when the national debt started going backwards," Barowitz said.

But it snapped back on in 2004 at 1133 Sixth Avenue, a block from its original location. Now located next to an Internal Revenue Service office — a coincidence that Barowitz calls "happenstance" — the clock had a quickie facelift in anticipation of a new clock.

"We pasted a dollar sign onto the clock," Barowitz said. "We’re going to design and build a new clock that will probably be up sometime next year."

The designers had better hurry. It may not be long before the American family's share will need a new 1, too.