Obsolete Skills

[Borodog]

Yeah. I better cool it before Anacardo shows up and throws a rod.

[MichaelL]

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I don't even know what a sine or a tangent or a cosine is. At all.

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They are made from some crap involving circles that I wont explain. Just look at the purdy graph!

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http://curvebank.calstatela.edu/unit/unit.htm

[Victor]

i went to europe "loosely" with 2 friends. i say loose bc we didnt have cell phones and constantly lost each other. we proly saw each other every 2 or 3 days on average. if it wasnt for the internet (meet me in berlin in 2 days k) we proly woulda never hung out.

so ya, meeting up with ppl.

proly already been said but i cant really emphasis how weird it was.

[mscags]

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1) cash register attendants: can't do simple arithmitic, i just feel bad for these people. It makes me realize how bad the education system is in our country.

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Bill is $5.61. They enter the cost and the amount you gave them ($10) and they see the result on the display ($4.39). You then proceed to hand them 11 cents. Watch with amusement at the resulting deer-in-headlights look and wisps of smoke curling out of their ears.

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I'm not sure why but this routinely [censored] up the workers in the USA, but in Argentina they seem to be totally on the ball with this even with weird [censored] like me giving them change to get back a 2 peso bill (1 peso is a coin) and other curveballs. I'm not sure why, but somehow these people getting paid $2/hr at McDonald's have better math skills than workers in the USA. Maybe it's because we don't realistically use another under 5 centavos and usually not even under 25 centavos. I admit 11 cents makes things ever so marginally harder for retards.

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Exactly the same in Spain weird, very strange. Lots of time they would actually go out of their way to ask for more change or whatever so they could give you back a certain amount.

[Anacardo]

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Yeah. I better cool it before Anacardo shows up and throws a rod.

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YOU CAN'T EVEN SPELL 'TANEY' YOU [censored] HACK

[WhoIam]

Knowing how to get relevant search results from altavista.com using boolean operators, etc. There's a reason Google has become the powerhouse it has. This is making me feel old--"damn kids today don't know what a hassle it was to browse through hundreds of search results trying to find one or two that contained the information you wanted.'

[Borodog]

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Yeah. I better cool it before Anacardo shows up and throws a rod.

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YOU CAN'T EVEN SPELL 'TANEY' YOU [censored] HACK

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Something like that. I heard it pronounced "Tawny" and couldn't remember how to speel it.

[Kimbell175113]

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Yeah. I better cool it before Anacardo shows up and throws a rod.

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YOU CAN'T EVEN SPELL 'TANEY' YOU [censored] HACK

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Something like that. I heard it pronounced "Tawny" and couldn't remember how to speel it.

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That is how it's pronounced, btw. Just one of those things.

[hobbes9324]

I didn't read the whole thread, so there may be someone else with the skill - I know how to use a slide rule. My dad was a mining engineer and taught me when I was about 8 yrs. old.....

Safe to say it's a lost art.....lol.

MM MD

[theblitz]

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By the way, if anyone doesn't know the simple techniques for taking square roots and logarithms in your head, I can explain it if you're interested.

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That'd be cool.

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Taking really quite accurate square roots in your head is pretty easy. You have to know the perfect squars, but most people know those (I hope). Say you want the square root of 70. Obviously 8.x (greater than 8, less than 9). Take the difference between the number you want the square root of (70), subtract the next lowest perfect square (64), and divide by 2 times the whole number part of the square root (8). So the square root of 70 is 8+(70-64)/(2*8) = 8 6/16, or 8 3/8, which is accurate to one tenth of one percent. It also works the same for the next highest square, too, if that is closer. So the square root of 78 would be 9 - (81-78)/(2*9) = 9 - 3/18 = 9 - 1/6 = 8 5/6. Accurate to about 2 one-hundredths of one percent.

Any time you want to take a square root of a larger or smaller number, just extract an even numbered power of 10 and repeat. So the squart root of 4200 is the square root of 42 times ten, or about 65. Accurate to three tenths of one percent.

Base ten Logarithms require a small amount of memorization, but the pattern is not hard:
log(2) = 0.3
log(3) = 0.5
log(4) = 0.6
log(5) = 0.7
log(6) = 0.8
log(7) = 0.85
log(8) = 0.9
log(9) = 0.95

Since log(ab) = log(a) + log(b), you can take any large number, like 3x10^8, and its logarithm is easily calculable: log(3x10^8) = log(3)+log(10^8) = 8.5 (recall that log(10^n) = n). Accurate to three tenths of one percent.

If you need to take logarithms of numbers where the lead number is 1 (where the log function rises most steeply), you can do it like this. Say you need the log(120). log(120) = log(3*4*10) = 2.1 (to about 1%). This works for other numbers if you need more accuracy. Like log(35). Instead of turning that into log(3x10^1) or log(4x10^1), just make it log(5*7) = 0.7+0.85 = 1.55 (to about 0.4%)

You can also take sines, cosines and tangents pretty easily and accurately in your head, or use the binomial expansion to raise numbers near one to high powers easily. All sorts of mathematical tricks that are lost on most kids these days.

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WOW.

I am 48 and never learnt those.
We used log tables.

I bought myself my first calculator at the age of 17.
It cost me $60!