A View from the Back of the Envelope top

Getting a feel for big numbers

... or how to develop numerical horse sense.

"[V]ery much the same as looking at the chairs in a room and guessing quickly if there are two or seven or fifteen" is guessing something's number of zeros, its "order of magnitude". With practice, one gets a sense for it.

To get big fast... count by tens.
"One, ten, a hundred, a thousand, ten thousand, hundred thousand, a million, ten million, a hundred million, a billion."

Getting a feel for how big... the "What order of magnitude is ..." game.
Are there 1, 10, 100, or 1000 people who can hear you shout now?

Getting a feel for really big numbers... with grains of salt.
If a bathtub of salt has a billion grains, then a 1/4 full tub has one grain for each person in the U.S. How many of them are male?

Also with Lots of dots and its A million dots on one page.

But often people don't do it...

"None of us really understands what's going on with these numbers."
David Allen Stockman, Director US OMB, on the U.S. Budget, 1981 [0]


The MegaPenny Project
Visualising Numbers

A View from the Back of the Envelope
Comments encouraged. - Mitchell N Charity <mcharity@lcs.mit.edu>



  2003-Feb-03  Fixed a link.
  2001-Jun-20  Added Mpenny link.
  mid 1990's   Created.