Fifty-five Minus Forty-five Equals Nine?

How much did Hillary Clinton win the Pennsylvania primary by? She got 55% of the vote, and Obama got 45%. 55%-45%=10%, and that's what the media seems to be reporting. But if you calculate the results she actually won by closer to 9%. Maybe not a lot of difference mathematically, but breaking the double-digit barrier is huge psychologically. So what's going on?

It's not some sort of anti-Obama plot by the MSM. This is just a classic case of the media dumbing down the news so they don't have to explain "complicated" concepts like rounding errors. Hillary got 54.7% of the vote, which rounds up to 55%, and Obama got 45.3%, which rounds down to 45%. The difference is obviously 10%, nice and neat. Wrong, of course, but nice and neat.