Wrapping your head around a trillion

K.C. Cole

TEXT OF STORY

Tess Vigeland: That the figure Steve just mentioned -- $2 trillion. You know I remember back in the day when a million dollars seemed like a lot of money. Now it seems like every day we're talking billions -- the stimulus package, the bank bailout.. Add it all up and you've got those trillions. Commentator K.C. Cole says wonders how we're supposed to wrap our minds around such a ginormous number.


K.C. COLE: The fact is, you can't -- because your brain is constructed something like a chessboard.

There's an oft-told tale about the fellow who invented chess, so delighting his ruler that he got to choose his own prize. He asked that one piece of grain be placed on the first square of the chess board, two on the next, four on the next, and so forth -- doubling the number of grains for each square -- right on up to 64. The resulting "prize" added up to more wheat than could be produced if every arable acre of land on earth were dedicated to it.

Why is that so hard to see coming? Because our brains count the squares, not the grains.

In a sense, our brains count only the logarithms of large numbers -- the power they are raised to, rather than the number itself. Two to the 6th power is only 64 grains. But two to the 10th power is already more than a thousand.

If you only count the difference between the power 6 and 10, you'll be badly misled.

It's the same with millions and billions and trillions. We automatically "read" a billion as about a third of a trillion. After all, it's only three zeros off. But of course, a trillion is a thousand times a billion, and a thousand is a lot.

Decrease your salary by a factor of a thousand, and it could go from 200,000 dollars to 200. Increase class size by the same amount, and your 15 students would turn into 15,000. It's roughly what happens when the "m" in million becomes a "b."

Our brains haven't evolved to directly deal with such staggering numbers, but we can use stories and metaphors to retrain ourselves.

So the next time a trillion begins to sound just like a billion, think about how you'd fare on a $200 annual salary -- or survive teaching a class of 15,000 students instead of 15, in the same classroom, with the same number of books.

Comments

I agree to American Public Media's Terms and Conditions.
With Generous Support From...