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Is this still a relevant skill-set to be good at these days? I feel like it's a bit like writing cursive or being able to have good handwriting in general. It's

• efaref 11y ago
  My maths teachers at school, like probably everyone else's, loved to tell us that we wouldn't be able to carry calculators around with us all the time when we're adults. The joke's on them. I carry a supercomputer with wireless access to the collective knowledge of humanity in my pocket. More seriously, if we assume we only have limited time and capacity to learn things, these tools surely free us from learning mundane "tricks" and allow us to further explore more interesting subjects. Sure, an understanding of arithmetic is important, so that we can verify our tools are working. But once that's obtained, let's move on.
  • jarcane 11y ago
    Yeah, except you look like a prick taking out your smartphone just to do some basic arithmetic. It's weird to me that a class of people who like to puff about how intelligent they are are so proud of refusing to function at an incredibly basic human skill.
    • babuskov 11y ago
      Showing your intelligence at full usually requires that you are not distracted. That is hard to come by these days. I can calculate 16x180 in my head, but I would still pull out my smartphone to do it if the result is in any way important. Not because I'm lazy, but I know that the device won't make some silly mistake while doing it.
      • Cyph0n 11y ago
        That's a trivial calculation to do, so I think it would be hard to make a mistake. I think you could have provided a better example. Edit: To the poster below, you only need the multiplication tables and basic addition. I don't see the big deal. 18 * 10 = 180 10 * 6 = 60 8 * 6 = 48 = 288
        • mobiuscog 11y ago
          I think you overestimate the capabililties of most people.
          • jjoonathan 11y ago
            16x180 ... = 288 I think he overestimates the capabilities of himself. He also misidentified the tricky part of the problem as multiplication and addition. Holding intermediate place values is far more likely to cause issues, as we can see from his mistake. If we allow for simple mistakes, everyone here can do that multiplication in their head without issue. But that was babuskov's exact point. Calculators help with silly mistakes of this sort and they're present nearly everywhere.
            • Cyph0n 11y ago
              I was calculating 18 * 16. For some reason I did not refer back to OP. The approach is similar however. I agree: holding values is quite difficult in many cases, but the whole discussion is about this example specifically. You only need to remember 3 values in this case, which should be easy for most people. And no I do not overestimate myself. I usually suffer from imposter syndrome.
        • hueving 11y ago
          12x12 is the max for most memorized multiplication tables (at least in the US). 16x18 is going to require some actual mental work that is prone to errors.
          • 11y ago
  • kqr 11y ago
    This is probably where I get bonus nerd points, but even before smartphones, it wasn't a huge hassle to carry a small slide rule. It still isn't.
  • gherkin0 11y ago
    Mine told me the same thing, and I listened. It turns out you can't think about numbers with a calculator.
    • Joof 11y ago
      Turns out you don't need many numbers to think about math.
• xiaoma 11y ago
  Don't you ever take notes? A lot of people still write. I mean pens are still sold at pretty much every convenience store in every country I've lived in. Learning cursive is so easy it's kind of amazing to me that some people, especially Americans, feel there's no ROI. Legibility on the other hand seems very easy for some and very hard for others.
  • pbhjpbhj 11y ago
    Which countries have you lived in? I don't think that convenience stores (aka 7-11s, spar, corner-shops, newsagents) in the UK normally have pens. I take notes in sermons/talks ... on my mobile [cell-phone].
    • deleted 11y ago
      [deleted]
    • nibnib 11y ago
      Are you serious? I think almost all small stores in the UK (and most of Western Europe) will sell you pens.
      • pbhjpbhj 11y ago
        I must be pen-blind ... will need to do research on my way home tonight!
        • pbhjpbhj 11y ago
          3:3 for having pens - TIL.
    • djhn 11y ago
      Sure they do. They sell lots of crosswords and puzzle books - clearly complementary goods.
  • falcolas 11y ago
    Worth remembering that cursive, as taught in America, is different than "joined writing" as taught in the UK. The American version is a bit harder to read and write, particularly the lower case 's' upper-case 'q' and both cases of 'z'. https://en.wikipedia.org/wiki/Cursive#/media/File:Cursive.svg https://en.wikipedia.org/wiki/Cursive#/media/File:Cursive.sv... vs. http://www.cursivewriting.org/joined-up-handwriting.html http://www.cursivewriting.org/joined-up-handwriting.html
• onion2k 11y ago
  I kind of agree. Most tricks are just a bit of fun. But some of the time when you need to do some mental arithmetic in the real world you're not actually looking for the right answer. It's more about estimating things. No one really needs to be able to multiply a pair of two digit numbers in their head, but if you're at a hardware store and you need to figure out how much paint to buy, being able to estimate the area of a wall quickly having a trick up your sleeve that gets you most of the way is very handy indeed. Also, a lot of the time these sorts of things aren't going to be used directly, but are more of an indicator of what to type in to a calculator. Knowing how to do something in your head informs how you do it on a calculator even if you don't actually use the trick yourself. A lot of people who are bad at maths don't even know where to start, so having a device to do the actual sums doesn't help them.
  • askafriend 11y ago
    I kind of agree with you too. As with most things, it's not black and white. It's a spectrum. And the usefulness has shifted toward the "less useful" portion of the spectrum whereas in the past, mental math was far more useful and the ROI on being good at it was greater than it is in the present. I'm not suggesting that you be totally braindead and not invest in learning the basics of mental arithmetic. I'm saying that going deeper than that initial basic investment isn't as useful today and doesn't make as much sense as in the past. For example, I'd consider the 75^2 example in this blogpost very cool, but not worth for me to deliberately remember and so I'm not going to commit it to memory.
    • shalmanese 11y ago
      Squares are worth knowing because a^2 - b^2 = (a+b) (a-b). This means any two numbers which are close together can be multiplied by finding the square of the midpoint. For example, 79*71 = 75^2-4^2 = 5625 - 16 = 5609. If you know your squares up to 100 and your multiplication tables up to 20, you can solve a great deal of two digit multiplication problems without having to reach for a calculator.
      • cozzyd 11y ago
• dragandj 11y ago
  Although I am not one of "math" people, I think that the pervasive opinion that "what I don't need in everyday situations and work I do not need" is a BIG mistake. Instead elaborating, I'll just make an analogy: We do not need to run, or to lift weights, nor exercise at all. We have transportation and tools. But, those activities are still highly valuable, even though we do not use them for work nor need them in everyday situations, because our body evolved to need them. So, math puzzles may not be directly useful, but they prepare the brain for other utilitarian activities. Ok, maybe we do not need puzzles, but math tasks in general is one of the best if not THE best exercise for abstract logical thinking.
  • kqr 11y ago
    Though exercising is not valuable because we need it, it's valuable because it keeps you healthy. I'm not sure how much evidence there is that maths keep you healthy. Sure, if you enjoy it, but if you hate it? At least exercise keeps you healthy even if you hate it.
    • dhimes 11y ago
      It is still good to have basic math numeracy, because swindlers are sadly not a dying breed. It's useful to listen to propaganda and have a feel for whether what the person is saying can even possibly be true. For example, if somebody says 40 million people in the US are [afflicted with|believe|whatever] something, I automatically think "that's about 1 in ten" and my bullshit filter makes a judgement. So getting precise numbers is perhaps not so important (maybe it never really was), but being able to estimate quickly it good. And, FWIW, you'd be surprised how well you can do at the grocery store if you estimate your bill simply by rounding every item to the nearest dollar. Easy to track, comes out remarkably close.
    • inanutshellus 11y ago
      You must not have retired grandparents... here's an old paper excerpt[1] about the "use-it-or-lose-it" nature of your brain: > The protective effects of an active cognitive lifestyle arise through multiple biological pathways, new research suggests. For some time researchers have been aware of a link between what we do with our brains and the long term risk for dementia. In general, those who are more mentally active or maintain an active cognitive lifestyle throughout their lives are at lower risk. New research throws some light on what may be happening at the biological level. [1]: http://www.sciencedaily.com/releases/2012/04/120425094358.htm http://www.sciencedaily.com/releases/2012/04/120425094358.ht...
• annnnd 11y ago
  Maybe not in the described form, but it is still very useful if you can do ad-hoc fast calculations. It helps when talking about budgets and similar - when someone throws some numbers at you it helps immensely if you can check if they are in the correct ballpark.
• ig1 11y ago
  In the startup world hugely. When you're running a startup your day-to-day life revolves around pricing models, conversion funnels, budgets, commission schemes, etc. If you're not able to do mental calculations while in the middle of conversations/presentations you'll get left behind by everyone who can.
  • kqr 11y ago
    I can imagine that. Me and my mom are of the calculating kind so when I visit over holidays it's not uncommon we sling a bunch of numbers back and forth over the dinner table to figure something out, and after we're done my dad and sister ask how we arrived at the third number from the first two. But in more "normal" social contexts, what tends to happen is one of the people involved sit with a digital calculator and input the things other people ask for. It's a bit slower, but the results are just as good.
• mmaldacker 11y ago
  This falls in the very specialized fields, but traders/brokers certainly need to be good at mental calculations.
• jonmrodriguez 11y ago
  At least in electrical engineering, we use mental math every day. More specifically, we use approximate mental math (trying to calculate to within about +/- 25% of the correct value) because it's faster than calculating the exact answer when we need a rough estimate of a power, current, voltage, or impedance number. I imagine that fast, approximate mental math is similarly useful in other engineering disciplines.
  • ThrustVectoring 11y ago
    Approximate mental math is really good for doing Fermi estimates, too.
  • alwaysdoit 11y ago
    One of the most important things I learned from my EE prof was that pi is 3. The square root of 10 is also 3. If you need more exact calculations, you should do it algebraically and then plug in numbers to a calculator, but for quick feasibility/sanity checks, approximate mental math is a very useful tool.
  • ajford 11y ago
    I was taught the importance of this in my first year of Physics undergrad. Fermi approximations (or order of magnitude estimation), from Fermi problems (https://en.wikipedia.org/wiki/Fermi_problem https://en.wikipedia.org/wiki/Fermi_problem). It is a highly valuable skill in STEM fields in my opinion. Sometimes knowing a rough number can tell you what to expect, and can immediately indicate whether something is wrong (or could go wrong).
• chenglou 11y ago
  Children in China remember the multiplication table from 1 to 10 at grade 3, as part of the curriculum, as well as additions and subtractions with arbitrary number of digits. Think of a piece of software where the hot paths get their result directly inlined for perf. Basic arithmetics occupy the "hot path" of your math curriculum until at least high school or beyond. This has a huge influence on reducing the amount of information you need to temporarily hold in your brain at once, leaving room for more important calculations such as exploring the solution space creatively, where one extra piece of information can make or break an insight. Similarly, you can certainly look up a frequently used word in the dictionary every time if you need to. But you might as well memorize the definition once and for all. Now it's a question of where to draw the line. For creative professions such as math/engineering/art, I'd definitely prefer hard-coding some calculations in my brain for the previously mentioned reason.
  • chestervonwinch 11y ago
    > ... leaving room for more important calculations such as exploring the solution space creatively ... Nicely articulated! And I believe the same applies moving ever higher up. Really, theorems in mathematics could be viewed in this manner -- do the proof once or twice for understanding and hard-code the result for use later in some larger context.
  • Joof 11y ago
    We call it memoization when it's for computers. People need 0-9 for basic algorithm, 10 is useful for decimals / notation, 11 is easy to learn and 12 is debatable, but potentially handy for base 12 systems which are fairly common. Beyond that we can learn fairly simple algorithms to do this sort of thing.
• manaskarekar 11y ago
  Then there's the unknown of how it may or may not improve your various brain functions/brain health, like physical exercise is believed to improve your physical health.
  • kqr 11y ago
    Doing things because they might be healthy is a pretty bad reason to do things. See also: alternative medicine.
• whatok 11y ago
  Being able to quickly sanity check the output of something has saved me from getting fired quite a few times.
  • Steve44 11y ago
    I think this is where a lot of people struggle. I can look at some figures and have a rough idea what the result should be, often that is all I need. If I need an exact answer I will work it out properly. Many of the people I work with can't do that - note I'm not in the IT industry any more where I think mental maths was more common. One example is I regularly get a spreadsheet with product and packaging weighs which we process for levy payments. It could be the weights of the carton, EPS padding, plastic bag sleeves for kettles; all the bits you throw away. My assistant didn't see a problem with a tiny plastic bag weighing 4Kgs, it should have been 4g. That was instantly obvious to me but clearly not to the supplier or my assistant. This is the ability to estimate and get a feel for the figures and although I find it frustrating I accept that many people have a big problem with thinking like that.
• elcapitan 11y ago
  I find myself calculating a lot in my head for example when discussing surveys, statistics etc, just to make some quick calc where certain numbers come from etc. Of course you could take out a calculator, but that's cumbersome in the middle of discussions for example.
• deleted 11y ago
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• wjnc 11y ago
  I dare say that in the various fields within finance, this skill is the true one-upmanship. A good working memory and enough calculatory skills to quickly glance over numbers and models to spot errors and interesting results pretty much defines your worth. In jest: two types of Excel-users. Those that use the model and those that don't trust the model.
• acqq 11y ago
  > Is this still a relevant skill-set to be good at these days? Yes it is! There's even a video https://www.youtube.com/watch?v=DZCm2QQZVYk&t=35s https://www.youtube.com/watch?v=DZCm2QQZVYk&t=35s "The greatest shortcoming of the human race is our inability to understand the exponential function."
• Aardwolf 11y ago
  > I feel like it's a bit like writing cursive or being able to have good handwriting in general. Does writing cursive refer to any writing at all, or do you mean a specific font? Writing in capital letters is sloooooow. If you cannot write, how would you write on a whiteboard, make mental notes, and so on?
• DanBC 11y ago
  > I feel like it's a bit like writing cursive or being able to have good handwriting in general. It's just not that useful anymore People teaching hand-writing today concentrate on speed and readability rather than beautiful writing. Some cursive forms are good for speed and readability. Taking notes is still an important skill for students, and computer note taking systems aren't always good enough. There's not much research, but the little bits that exist suggest that taking notes helps people learn. Some systems, like Briem, are fast and look neat enough but can end up as hard to read zig-zags. http://briem.net/ http://briem.net/ This (weirdly expensive book) has details of how writing systems have changed over the years. http://www.amazon.co.uk/Handwriting-Twentieth-Century-Rosemary-Sassoon/dp/0415178827 http://www.amazon.co.uk/Handwriting-Twentieth-Century-Rosema...
• caseysoftware 11y ago
  I am one of those people good at mental math - enough that our founders turn to me in meetings - and I think it's useful. Instead of thinking of it as a skill, think of it as an exercise. There are hundreds if not thousands of things trying to distract, mollify, enrage, and lull us into a "don't think, just act" attitude... having mental fortitude to counteract or ignore those is important.
• aptimpropriety 11y ago
  Mental math (and arithmetic tricks) are pretty important for scoring high on the GMAT (for MBA admissions). No calculator is allowed, and while you can solve by pen and paper, for a very time constrained test, tricks can be the difference between a good and great score. It's also somewhat valued in the business / consultant crowd for talking through assumptions and making estimates of problems.
• tetraodonpuffer 11y ago
  when all you have is a hammer, every problem to solve looks like a nail, the more mental tools you have the more likely it is that you'll see patterns or solutions that you wouldn't see otherwise. The human brain is not a machine that becomes more "optimized" the "less services are running", the more knowledge the better, even in fields that might seem only barely tangential to where your main interests lie
• NoMoreNicksLeft 11y ago
  I wonder how much of a kickback Ford and GM would pay for my completely independent iPhone app that gives bad car-buying advice?