I remember

 

I remember learning in school about significant digits and accuracy.  The number of significant digits you have defines the confidence you have in your number.  If you add, multiply, or divide, you only have as much confidence in the result as the lowest number of significant digits that went into it.  If you’ve got a weight measured to 17.2857 grams, you’ve got 6 significant digits of accuracy.  That’s accurate!  If you multiply it by a number, like 3.14, you get 54.277098, but not really; you don’t get an answer accurate to 8 digits.  The number you get is only as accurate as the least accurate number you used in your calculation, so the answer you have confidence in is really only 54.3.  A lot of the accuracy of your original weight just went away in the calculation, from 6 significant digits to 3.

 

This was all brought to mind while driving down the highway; seeing the construction sign that announced the total cost of that project to be $45,172,843.10.  Really?  And ten cents?  Not eleven cents, ten cents!  I realize that a highway construction project is not bound by scientific accuracy, and there might be a fixed contract that specifies that exact amount, but how much useful information did that ten cents add?  Two significant digits $45,000,000 might give us all the information we need, maybe three $45,200,000.  Surely everything after the first five digits $45,173,000 is just clutter.

 

 

We’re still at Rusty’s.

 

Watched curve-billed thrashers.