Do you do simple math "out loud" in your head?
LostAngeles
Penultimate Amazing
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Brian said:
I was afraid it was going to come off as me going "j00 DUMB," s'all.
Very happy that it didn't. Teh INTARWEB is a very precarious place at times.(It's 4, btw.
)aofl
Muse
- Joined
- Jan 18, 2005
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- 505
LostAngeles said:
That's how I was taught, too. But a couple of years ago I started adding left to right after reading the book Miracle Math by Harry Lorayne. Stupid title, but the techniques for addition and subtraction I found useful.
When adding from left to right it's usually not too hard to look ahead and see if you need to carry a 1. Plus you are computing the number in the order it would be written and computing the most significant part of the value first.
So, e.g:
97 + 48
Start by saying "one-forty" because 9+4 = 13, but there will be a carried 1, and then finish saying "five".
It works for me.
A
Diogenes said:
I got it from the person who actually said it, not the person you are quoting. You have been following along, haven't you?
In fact, I got it from this post from Diogenes:
" Uhhh.. Did school let out early today?
Believe it or not, there was a time ( only about ~ 25 or so years ago), when order takers at restaurants did not use a cash register to take orders. They wrote them on paper.. They may have been entered into a register later by a manager.."
Are you now invoking Retard Rules? Because it's only fair to say so up front. Otherwise, I will continue to assume you have grade school reading abilities, at least.
All this fascination with urine see below and school is disturbing, to say the least.
Clearly you are wrong. See above.
Res ipsa loquitur.After having wet yourself, thinking you had caught Brown making up a story, you are furiously backpedaling, hoping no one will notice..
Since you feel " last word = win ", go for it, and congratulations in advance..
P.S.
Psssst . Brown, I know you are above this and don't need defending, I just don't have anything better to do right now..
Beth
Philosopher
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- Dec 6, 2004
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TeaBag420 said:
Not made up, just gives away his age. Old cash registers would ring separate items on a bill, but they didn't compute tax or do subtotals. You had to sum the items, find (or compute) the proper tax amount for it and then add that to the bill. Then you could ring it up on the cash register - after you had done all that math by hand.
Beth Clarkson said:
Do you know how crazy that sounds? Please to be providing an example of a cash register that didn't add up the total amount of the sale, and explaining why not just use a typewriter or a notepad instead.
My father's in his eighties and I checked with him. Cash registers in his day (childhood) gave the total amount of the sale. No one said anything about taxes or subtotals, and I say you are wrong about that anyway.
http://en.wikipedia.org/wiki/Cash_register
TeaBag420 said:
How about we stop arguing about crap that is a matter of historical record and easily resolved with some research? You might find, for instance, that an octogenarian would have been born in the 1920s decade. You might also find that the cash register was invented in 1884, instantly rendering the octogenarian's childhood recollections a non-expert source on what the first cash register was and wasn't capable of.
Beth
Philosopher
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TeaBag420 said:
No, I don't know how crazy it sounds. I'm giving my age away too, but as a teenager I worked with such cash registers. As far as taxes or subtotals go, that might be what the original poster was referring to in adding up a tab of items at McDonalds. He/she didn't specify and that was my experience though not at McDonalds. I worked at my father's small town store which used what was considered to be an old cash register back in the 60's. (It was probably 30 or 40 years old back then.) The tax and subtotal part is explaning why someone would have to do all that math prior to ringing the sale up on the cash register. The original post did not sound like a made-up story to me. It sounded like experiences I had had. Some customers were quite suspicious of someone who added the bill too quickly.
Beth
Beth
Philosopher
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BillHoyt said:
I've given up on this particular strategy. I never did to confound people anyway, I did it just because I don't like having a lot of loose change and used to try and minimize the change I got. Even back in the 60's and 70's, a certain percentage of people would get confused by it. I haven't tried in years at this point though. I got tired of people giving me a blank stare, counting out the change from the bills and handing me back the change I had given them. They just thought I couldn't count and had given them too much money.
The fun really begins when you ask the fellow with the pocket protector who just handed you the change "Don't you don't speak English?"BillHoyt said:
I always kept a dollar bill that I had put in nasty places on my body for customers like this, and I'm not the only one. Verbum sap.
Skeptical Greg
Agave Wine Connoisseur
Working in the kitchen now, are you?TeaBag420 said:
Rolfe
Adult human female
I just think this is a weird conversation. I often "overpay" by a few pence or whatever to make the change neat, because I don't like carrying a lot of coins in my purse. I don't think I've ever had a shop assistant not instantly twig what I was doing, and hand me back the correct change as a fiver, or a pound, or whatever.BillHoyt said:
Do you have real thick shop assistants in Merika or what?
Rolfe.
TeaBag420 said:
What exactly is supposed to be so wrong about a customer wanting a quarter back instead of 11 cents? What the heck is wrong with you? If a cashier similarly says to me "can you give me a $1 bill and I'll give you $10 back", should I complain to his/her manager?
rppa said:
What's wrong with me is that I'm bothered by someone who doesn't want compact change per se; it's the fact that he's a mean person who enjoys playing "tease the retard". People generally pick up on that and he's probably been the recipient of more bodily fluids than he knows.
When I give extra change, I generally say aloud the change I expect back. This way both people walk away happy. I get compact change, and I haven't humiliated someone whose parents and teachers failed him. That's not the sort of thing that gives me pleasure. But giving that guy my love on a burger would be a mitzvah.
fishbob
Seasonally Disaffected
Oh yeah.
CurtC
Illuminator
A neat trick for multiplying two numbers sometimes is the identity:
(n+1)(n-1) = n^2 - 1
So, for example, if you need to multiply 15 times 17, you just square 16, and subtract one. 18 times 22 is 396 for the same reason. If the two numbers have an even difference, and you know the square of the number halfway between, it's a quick way to do it and can be impressive.
The calculation trick that I'm pretty good at is calculating the day of the week for any arbitraty date. Say somebody asks what day of the week May 31, 1961 (my birth date) was on.
Start with the year - 1962 was a zero-year (I have a list of these memorized), so you subtract one for 1961, and there were no intervening leap years. So far, -1.
Now you add a number corresponding to the month, which I also have memorized. May is zero, so we still have -1.
Now add the day to it and you get 30, and modulo seven leaves a result of two. Monday is zero, Sunday is six, so I was born on a Wednesday.
I can do this in about five seconds, but if you start out asking someone the year and get that data first (or make an educated guess for the year), you can be calculating the hardest part while you then ask for the month, then the day. It's kind of a magician's trick in that way, but using that distraction technique I can often nail the correct weekday in a second or two. Then I tell people I'm an idiot savant, which they usually half-agree with.
(n+1)(n-1) = n^2 - 1
So, for example, if you need to multiply 15 times 17, you just square 16, and subtract one. 18 times 22 is 396 for the same reason. If the two numbers have an even difference, and you know the square of the number halfway between, it's a quick way to do it and can be impressive.
The calculation trick that I'm pretty good at is calculating the day of the week for any arbitraty date. Say somebody asks what day of the week May 31, 1961 (my birth date) was on.
Start with the year - 1962 was a zero-year (I have a list of these memorized), so you subtract one for 1961, and there were no intervening leap years. So far, -1.
Now you add a number corresponding to the month, which I also have memorized. May is zero, so we still have -1.
Now add the day to it and you get 30, and modulo seven leaves a result of two. Monday is zero, Sunday is six, so I was born on a Wednesday.
I can do this in about five seconds, but if you start out asking someone the year and get that data first (or make an educated guess for the year), you can be calculating the hardest part while you then ask for the month, then the day. It's kind of a magician's trick in that way, but using that distraction technique I can often nail the correct weekday in a second or two. Then I tell people I'm an idiot savant, which they usually half-agree with.
voodoochile
Thinker
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For large numbers, the distributive property works well.
45 * 48 = (50-5) * (50-2) = 50^2-7*50+10 = 2500-350+10=2160.
A trick on the celcius conversion is that most everyday numbers aren't going to be seriously degraded by taking a rough stab.
to convert C to F simply double the C and add 30 for a rough estimate.
In the -22 example, the conversion comes out at -12 not -8, but really, how important is that 4 degrees unless you are doing something highly scientific.
The more extreme the numbers, the greater the error, but since most people don't ecncounter temperatures outside of the 0-100 F range on a regular basis, it really isn't that drastic of an issue...
Now converting ML to OZ is a different story...
45 * 48 = (50-5) * (50-2) = 50^2-7*50+10 = 2500-350+10=2160.
A trick on the celcius conversion is that most everyday numbers aren't going to be seriously degraded by taking a rough stab.
to convert C to F simply double the C and add 30 for a rough estimate.
In the -22 example, the conversion comes out at -12 not -8, but really, how important is that 4 degrees unless you are doing something highly scientific.
The more extreme the numbers, the greater the error, but since most people don't ecncounter temperatures outside of the 0-100 F range on a regular basis, it really isn't that drastic of an issue...
Now converting ML to OZ is a different story...
Or you could just multiply the two numbers, like a person, like a mensch. If you think 48 is a large number you have problems.voodoochile said:
45*48
1600
320 1920
200 2120
40 2160
--------
2160
Yes, it's much more straightforward, since it doesn't involve an offset. Ohhh, I get it, you were making a getting drunk joke.
Don't take it personally, that's the kind of treatment you can expect here. People will give you shitbecause their pocket protectors are irritating them. The metrosexuals among them will spell it "◊◊◊◊◊" and in some cases their caregiver or partner will help them type "shiite" because they don't know how to type "◊◊◊◊◊".
And of course "◊◊◊◊◊" doesn't get censored, and it helps you get laid with goth chicks down at the local. rosnec eht no tihs. ◊◊◊◊◊, ◊◊◊◊◊, ◊◊◊◊◊. ◊◊◊◊◊ all day long, and in many positions. ◊◊◊◊◊, ◊◊◊◊◊, ◊◊◊◊◊. ◊◊◊◊◊, I say. ◊◊◊◊◊. Shid. Zhit. Merde. Sheiss. ◊◊◊◊◊. ◊◊◊◊◊.