Saturday, June 25, 2005

Emergency ruler

I'm sure I'm not the only one who has noticed this, but I discovered this on my own, and I'll take whatever credit folks want to toss my way.

Here's a handy way to make a ruler with nothing more than an 8.5x11 inch piece of paper. Holding it as a portrait (taller than it is wide) fold it on a diagonal line so that the bottom edge lines up with the left side (or the right side, if you are so inclined). When folded, you'll have a skinny rectangle at the top which you could cut off, leaving you with a piece of paper 8.5 inches square.

The long diagonal of an 8.5 inch square happens to be just two hundredths of an inch longer than 12 inches. Close enough for government work, as they used to say down on the farm.

Fold that line in half, and you have the 6 inch mark. Fold in quarters for the 3 inch and 9 inch marks. I'll leave it to you figure out how to get the rest.

3 comments:

Richard Lawrence Cohen said...

My kids will like this, and I think my wife will too. She's an elementary math researcher at the University of Texas. You might like her professional blog for elementary math teachers and researchers: Learning Math, Teaching Math

(And I was a stay-at-home dad for six years, 1981-1987, so we have something in common.)

Welcome to the blogosphere!

peter hoh said...

Richard, having just read several of your wife's entries, I'm sure that she'll be interested in the various strategies people employ to make the other inch marks. I find that using another piece of paper is simplest approach.

As for being a stay-at-home dad -- did you find that the "gap" on your resume made it hard to re-enter the workforce? When I chose to stay home, I passed up an opportunity for a lateral career shift that is most likely never going to arise again. I suppose that's fodder for another post.

Stacey said...

Very interesting... Good ol' Pythagorean Theorem put to use. For those that don't know...

a squared plus b squared equals c squared.

a, b, and c are the lengths of the sides of a triangle.