# Tag Archives: geek

## How to memorize the value of e to 15 decimal places

I learned the following trick for memorizing the value of e from my colleague, Gene White. It never fails to impress calculus students (given a wide enough definition of “impress”).

Start by carefully looking at this picture:

That’s a 20 dollar bill, so memorize “2” and put down the decimal point.

The picture on the bill is of Andrew Jackson. He was our seventh President, so put a “7” after the decimal point to get 2.7.

Jackson was elected in 1828, so put down “1828” next. Since there’s a 2 in front of the decimal place, put “1828” a second time. We’re now up to 2.718281828.

Now look at the red square over Jackson’s face. The diagonal creates two congruent right triangles with angle measures 45, 90, and 45. So, add on 459045 to get 2.718281828459045. And that’s e to 15 places.

I’m open to suggestions on how to memorize more of the digits.

Filed under Calculus, Geekhood, Math, Teaching

Here’s a list of 50 Books Every Geek Should Read from InsideTech. I thought this list might go well with my request for basic reading in educational technology from a few days ago, and in fact there could probably be some overlap.

Of the books on the list, I’ve read:

For math geeks, and perhaps for general geeks, I’d add G. H. Hardy’s A Mathematician’s Apology. For higher education geeks, add on The Shadow University by Kors and Silverglate.

I think Longitude is going to go in my personal queue next.

Filed under books, Geekhood, Math, Technology

## (Super-)Powers of 2

Driving in to work this morning, I suddenly felt my vision go blurry to the point where I literally couldn’t see anything. Fortunately, I was able to pull off the road into the parking lot of a small office building before causing an accident. After I stopped and waited for the blurriness to subside, the first thing I saw was the mailbox for the office building, which had a street number of: 2048. Rather than wonder what the crap was wrong with my eyesight, or frantically try to decide whether to go see a doctor on the spot, instead the first thing I thought was hey: That’s $2^{11}$

Then, after making it to work with no more blurry vision attacks, I walked up to my office — the same office I have been entering and exiting since summer 2001 — and looked at the office number and saw it: room 128. Of course, I’ve never had a problem remembering my office number But for the first time in seven years, I noticed, hey: that’s $2^{7}$

So, maybe the blurry vision attack was me suddenly gaining the superhero power of being able to recognize powers of 2 with lightning quickness. If so, I somehow don’t see the Justice League of America saving me a seat anytime soon.