The math behind a neat calculator trick

http://divisbyzero.com/2010/02/17/the-math-behind-a-neat-calculator-trick/

by signa11 • 16 years ago

74 17 16 years ago

te_platt• 16 years ago

If you want to work it out yourself first here is the trick. Set calculator to degree mode, enter a bunch of fives (5555 or 55555555), take the reciprocal, take the sin, note similarity to pi. Very fun article.

hackermom• 16 years ago

pi / 180 = 0.01745 (a value commonly used for degree<->radian conversion). 1 / 180 = 0.0055555. That's the connection between the "magic" constants used in this trick.

It brings an older, simpler, not nearly as interesting calculator "trick" to mind: 11111111 * 11111111.

imurray• 16 years ago

It brings an older, simpler, not nearly as interesting calculator "trick" to mind: 11111111 * 11111111.

  gnuplot> pr 11111111 * 11111111
  -2047269199

:-). For the intended result, people can put a '.' after one of the numbers to make it a double, or use a better calculator like bc or Python.

hugh3• 16 years ago

Sure, but can anyone explain 5318008?

est3• 16 years ago

for those of you who didn't get it

http://www.urbandictionary.com/define.php?term=5318008

mhd• 16 years ago

Walking upright shifted our focus away from butts?

jpeterson• 16 years ago

Wow, I can't believe this made it to the top of Hacker News. Tranformation to Reddit complete!

Shamiq• 16 years ago

Oh no.

gokhan• 16 years ago

Calc's are funny.

Try 12345679 * 9x (where x < 10)

csomar2• 16 years ago

So what will happen? (tried on all my calc's and they gave the same result as http://www.google.com/search?q=12345679+*+92, which I think it's correct).

CrazedGeek• 16 years ago

Try 123456789 * 9 * 2.

dutchflyboy• 16 years ago

While the trick is quite nice, I personally just press the "PI" button...

cliveholloway• 16 years ago

Much too highbrow for me.

39103 * 136

Then turn your calculator upside down and read the result.

est3• 16 years ago

Here is how to get e using a calculator:

sinh(1) + cosh(1)

The math behind a neat calculator trick

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