The very many questions-not-worth-their-own-thread question thread XXVII

[Takhisis]

I'd do the other way round: first add 10, getting 36, then add 7.

Yeekim, my man! Great minds think alike!

 

[Kennigit]

I dont know any results of the common core, but sometimes when I see common core stuff or people talk about intuitive it seems to "optimize the wrong problem"

This number adjustment method, to me, seems rather inapplicable if you want to ask what 1234 + 5678 is. Id break it into chunks--1200 + 5600 + remainder. Of example earlier, 20 +6 + 7 + 10 or any order of those groups, i e. I can just do 26 + 17 directly for the most part, probably as 26 + 7 + 10

Like i feel sig figs should be intuitive and not adjusting things up or down but clumping in groups. 4567890 + 1423 is about 4570000

 

[Timsup2nothin]

I always work from the most significant digits.

26+17...20,30,36,43

1234+5678...6000,6200,6800,6830,6900,6904,6912

I think this is an advantage because sometimes if you start from the most significant digits you find out that you really can't be bothered with the rest...say if you are adding up radiation exposure rates from multiple sources, for example...not that I learned this in the navy or anything...

 

[Takhisis]

I sometimes use Timsup2nothin's method. For rough estimates (say, adding football match attendances) it works fine. For fine detail I do it the other way around, starting with the units, then the tens, hundreds and so on.

 

[Hygro]

I always work from the most significant digits.

26+17...20,30,36,43

1234+5678...6000,6200,6800,6830,6900,6904,6912

I think this is an advantage because sometimes if you start from the most significant digits you find out that you really can't be bothered with the rest...say if you are adding up radiation exposure rates from multiple sources, for example...not that I learned this in the navy or anything...

So this is me: take your 1234+5678 example. My mind goes
uhnn 68, 69 82 112 6912 in one stream of consciousness. Definitely not how it was taught to me but definitely is how I outperformed the suckas who didn't have a fast method.

 

[Borachio]

I don't get why you've put a 112 in there. I'd go 68, 69, 6912.

Actually, I wouldn't at all. I'd go 12, 112, 712. No. B888er it. Where's a piece of paper?

 

[Mise]

1234 + 5678 I would just approximate, aint nobody got time for that. 234 + 678 ~= 1000; 1 + 6 = 6, so the answer is ~7000.

If I need to know the last digit (say if I'm checking a calculation that someone else has done) then I know the last digit is a 2.

Those are really the only two things I would do with those numbers in my head.

 

[Antilogic]

You can tell who the engineers are.

 

[Hygro]

I don't get why you've put a 112 in there. I'd go 68, 69, 6912.

Actually, I wouldn't at all. I'd go 12, 112, 712. No. B888er it. Where's a piece of paper?

78+4+30=112, but I already know the 69 includes the 100 so instead of adding the 112 to the 69(00) I merge the overlap (or drop the 100 if you like) and just add 12. I'm solving the equation while estimating the answer to make sure I don't miscalculate as I calculate quickly.

 

[Sanguivorant]

Guys how do I quickscope?

 

[Takhisis]

What the hell is quickscoping?

 

[Antilogic]

I thought he said quickstroke, glad I didn't post any instructions.

 

[Takhisis]

Well, not I want to know about both!
(It's certainly more interesting than rereading The Catcher in the Rye for the umpteenth time)

 

[Hygro]

SAFE SEARCH ON! SAFE SEARCH ON!

 

[Borachio]

A person who quick scopes will use a sniper rifle, but instead of aiming down the scope like sniper riffles were made for, they exploit a feature and shoot when the cross hairs meet, resulting in a one hit kill, despite the fact a majority of the time the cross hairs miss the target. Then when somebody uses a sniper riffle for what it was meant for and look down the scope, the people who quick scope yell at the player who looked down the scope and call them a "hard scoper"

Quick scope.

Quick stroke is a technique in swimming. I know nothing about it; as I vary my stroke between slow and drowning.

Spoiler :

Honestly, the other day I had to be fished out of the pool with a long pole. How embarrassing!

Spoiler :

I lie. But I don't swim well.

 

[sophie]

Well it would have been nice to have been taught the method that was more intuitive to me up front, instead of being told that there is one and only one way of adding up and if you do it any other way then you're adding up wrong...

And it wasn't really until I was older that I started doing it differently. Imagine how much easier it would have been in primary school if I had been taught the other method.

Seriously, you're simply opposed to it for the sake of it Quackers. This is allowing children to learn basic maths in a way that is more intuitive for each individual. It would have helped me and I'm sure it will help other people to learn maths a lot easier. I just can't see how any rational minded person would be so reflexively opposed to this, without even a scrap of evidence or teaching experience...

I haven't read the rest of this discussion, so I don't know if it's mentioned, but I believe educators doggedly teach you the "carrying" method of adding because it scales up very very easily. It might take you a bit longer to do 17+26, but when you get bigger numbers like 1,357+4,319 or 126,986+1,189,957, a) the amount of time required doesn't change, and b) the system of solving is exactly the same, just with more columns. Same with subtraction, multiplication, and long division. That being said, I don't know if it's different in the UK, but in the US we were taught mental math in addition "proper adding". We learned those simple shorthand techniques for easy addition and subtraction.

 

[Zelig]

Clever tricks scale up to large numbers too - Feynman talks about how he does mental arithmetic with large number. The idea with manipulating numbers for mental arithmetic isn't to manipulate them in a specific way, it's to do whatever works best in your head.

If I'm doing 1357 + 4319 I probably do 57 + 19 = 57 + 20-1 = 76 + 1300 + 4300 = 5676.

 

[Hygro]

I look at that and go

unhhh 56, nn 60 70....6 so 5676

it's all verbal in my head with a visual intuitive anchor flashing responses.

 

[Kennigit]

I thought feynman was more about logs, ln, and exponential functions a^b rather than "large numbers" in surely you're joking

 

[Zelig]

I thought feynman was more about logs, ln, and exponential functions a^b rather than "large numbers" in surely you're joking

I haven't read it in a while, but that seems reasonable, adding large numbers isn't very interesting, and the concepts are the same.