Japan’s soaring national debt, already more than twice the size of its economy, has reached a new milestone, surpassing one quadrillion yen.

Let the word quadrillion roll around in your brain for a moment or two, because it is not something you hear every day. Quadrillion. 1,000,000,000,000,000. Really.

A paltry million is the numeral one followed by six zeros. A billion? Nine zeros. A trillion is getting up there: 12 zeros. But the mighty quadrillion has 15 of them.

The mind boggles. (Though it doesn’t googol: that one is followed by 100 zeros. And that’s the actual spelling. You can Google it.)