4 ms·

Because you need to be able to run numbers in your head for a lot of practical tasks, and inability to do napkin math can cost you very dearly

by ein0p 2y ago

throwway120385 2y ago
And calculators get broken very quickly on construction sites. And you must be capable of adding and subtracting and finding the LCD and GCD of fractions to read a tape measure in US customary units.
- QuercusMax 2y ago
  There must be ruggedized calculators out there, so that argument doesn't seem very compelling. People use their phones at construction sites, and you can run whatever type of calculator you want on a cell phone.
  - bayindirh 2y ago
    If you run every basic calculation through a calculator, you'll make every task take 3x time it requires today, in best case. I have seen people eyeball measurements and taking notes, and bringing in perfectly manufactured goods (blinds, cupboards, etc.) in return. Esp, in construction, nothing is precise, so being able to eyeball correctly after a quick measurement with a tape and doing some basic math on the numbers, not only accelerates tasks, but is a crucial pillar of being able to work on construction sites, and be productive.
    - ToucanLoucan 2y ago
      I just left a comment on a different thread about detached from reality a lot of tech workers are, and then here I find a guy being like "but rugged calculators are a thing, why do you need to do math in your head?" Tell me you have never built a thing[1] in your entire life that was more complex than an IKEA bookshelf without telling me that challenge: I do hobby projects all the time and I couldn't even tell you how many mental-math problems I do per hour while doing so. It's a LOT. Depending what I'm making I might well spend more time doing math in my head and on paper than I do actually putting tools to materials to build the thing. [1]: by this I mean actually building. With your hands.
      - QuercusMax 2y ago
        I never said you don't need to do math in your head. I said that the argument "calculators are fragile, so you have to do math in your head" doesn't hold water. You're arguing something different, which I tend to agree with.
      - nerdponx 2y ago
        Hell even installing shelves in my closet had me doing trigonometry on a scrap of printer paper to figure out how close I could space together the shelves and still be able to get the boards through the door frame. Calculation is one of the core skills of human cognition and is correspondingly foundational for just about all of human enterprise. Not doing it means limiting your ability to participate in said enterprise.
- KeplerBoy 2y ago
  What is going on with your tape measures? Confused european over here.
  - ein0p 2y ago
    Customary units are given in fractions of an inch. Eg half, quarter, eighth, sixteenth etc. So you’re dealing with simple fractions. That is why I buy tape measures that also have metric scale - to sidestep all that bullshit entirely when adding, multiplying, dividing or subtracting, yet be able to measure distances in inches too
    - ssl-3 2y ago
      I keep a fractional-inch tape measure in the toolbox in my work truck because that's what everyone else (in the US) has, and I need to be able to work with others. I also have to carry around two sets of wrenches, two sets of sockets, two sets of Allen keys, and it's all quite frankly absolute bullshit. But that's the world I get to participate in. At home in my own geeky little workshop, where I don't need to satisfy anyone else's proclivities, everything is exhaustively and exclusively metric-only. My tape measures are metric, my hand tools are metric, my drills are metric, and my fasteners are metric. Working with Freedom Fractions is absolutely forbidden in my workshop (as are all screws with Phillips, JIS, Pozidrive, or Reed-Prince heads, but that's a different rant). And, I must say: It's better this way.
      - nerdponx 2y ago
        > screws Torx?
        ssl-3 2y ago
        For screws that go into wood (or thereabouts; sheet metal screws can count here too), Robertson is first on my list. The slightly tapered interface fits snugly and tends to hold screws onto a driver bit very well while providing good angular alignment, and it can do all of this without needing magnets. It can also allow for a bit of angular misalignment when necessary, and the chonky squared-off corners and flats resist cam-out/stripping rather well. I'm not even Canadian and I use Robertson wherever I get a chance. Second general choice is hex-head screws. These snap into inexpensive shallow magnetic driver bits with a satisfying click. But they're ugly and kind of rough once installed, and they're not available in flat-head versions. (Hex-head shoulder screws are my only choice for drill-point screws: They maintain positive angular alignment by default and that's crucial for drilling holes in metal.) Torx is fine too, I suppose. I don't have an anti-Torx rule in my workshop, but I try to avoid buying them. They don't tolerate angular misalignment as well as Robertson, and they don't maintain positive angular alignment like a hexagonal shoulder screw does, and they don't stay put with friction like Robertson or snap onto a magnetic driver bit like hex. There's lots of stuff Torx is not very good at doing. Theoretically, I can probably put more torque into Torx than any of the other options listed here, but I don't find that to be a practical advantage in this kind of application: When I can already drive a Robertson screw through a chunk of old-growth wood, I don't need to improve that part. --- For machine screws, I've standardized on stainless steel button-head socket cap screws as a first choice. I've got a deeper selection of them than a good hardware store does, and they're all sorted. (Why stainless instead of graded? Because I don't want them to rot, whether sitting in a bin for decades or used outdoors or whatever and I do not want to stock more than one kind. My fastener collection is crazy enough without also multiplying it by different grades.) There's other stuff, though, too. For instance: Regular socket cap screws have their place -- it just isn't first place. And at the scale of things I build, I mostly use M3, M4, and M5. I buy regular-length Bondhus non-ball hex keys in simple bulk packaging to fit my standard M3, M4, and M5 machine screws. They're very high quality tools, and they're rather inexpensive in bulk. And thus, it is no big deal if I misplace one while I'm working -- I've got more on-hand, and I'm not afraid to get more coming if stock gets low. Bondhus makes a decent-quality hexagonal screwdriver, too, and these are nice to keep around because the design is not like the gigantic T-handled abortions that so many other manufacturers sell: It's just screwdriver-shaped, and it works just like a familiar screwdriver does -- but for socket-cap screws! This was the discovery that allowed me to completely abolish Phillips screws forever from my workshop. I've also got sets of hex keys -- of course I do. Long, ball-end, plain, whatever. I try to avoid cornering myself into a situations where these non-regular variations would ever begin to be useful to begin with, and the long versions are mostly only useful for disassembling stuff that someone else had overtorqued. (But overtorqued fasteners are different rant.)
- akira2501 2y ago
  > and finding the LCD and GCD of fractions to read a tape measure in US customary units. Well, that's what tolerances are for. I don't need a perfectly accurate answer. Just one that's within 1/32" or more likely 1/4" to 1/8".
  - throwway120385 2y ago
    I don't see what tolerances have to do with it? You still have to do math if you have to site a member between two other members regardless of the tolerance. For example, to frame an 8 foot wall you have to cut your studs down to accommodate the top plate and bottom plate and the trim plate above the top plate. Similarly with windows, doors, and headers. Whether you have a 1/16 tolerance or a 1/8 tolerance it doesn't matter. The only time I've had to deal with tolerances when framing is in making sure the drywall doesn't wave anything around by firring out or planing down each stud to put the wall into tolerance.
    - akira2501 2y ago
      The idea that you have to do a full LCD or GCD to work with fractions in engineering or building is not rational.
- ssl-3 2y ago
  If durability is the chief constraint, and tape measures are adequately durable and already on-hand for the work being performed, then: The tape measure itself can be used to perform basic arithmetic, and will even return results in Freedom Fractions if that's how it is labeled.
AlanYx 2y ago
This isn't just folk wisdom either. There's an active subfield of cognitive science that focuses on working memory/cognitive load and math instruction. Broadly speaking, it's hard for students to successfully transition to even basic algebra if they don't have basic calculations down.
- Ntrails 2y ago
  That fits with my non expert intuition. If you don't get the basics of arithmetic it is incredibly hard to grasp the idea of "equals" as a pivot point. Division by hand helps to give us a hint that numbers can be broken up into constituents and still be the same. You internalise a whole set of behaviours, typically via repetition, and it unlocks understanding beyond itself imo
- abdullahkhalids 2y ago
  It's all about building higher and higher abstractions. Arithmetic - > Algebra -> higher order algebraic algorithms. For example, when I taught differential equations, my non-scientific observation was that otherwise smart students struggled more with getting the algorithms down, if they struggled with algebra. Having to constantly jump down to a lower level of abstraction while performing the algorithmic steps is what caused confusion to mistakes.

Because you need to be able to run numbers in your head for a lot of practical tasks, and inability to do napkin math can cost you very dearly

by ein0p 2y ago

Because you need to be able to run numbers in your head for a lot of practical tasks, and inability to do napkin math can cost you very dearly

throwway120385 2y ago

And calculators get broken very quickly on construction sites. And you must be capable of adding and subtracting and finding the LCD and GCD of fractions to read a tape measure in US customary units.

QuercusMax 2y ago
There must be ruggedized calculators out there, so that argument doesn't seem very compelling. People use their phones at construction sites, and you can run whatever type of calculator you want on a cell phone.
- bayindirh 2y ago
  If you run every basic calculation through a calculator, you'll make every task take 3x time it requires today, in best case. I have seen people eyeball measurements and taking notes, and bringing in perfectly manufactured goods (blinds, cupboards, etc.) in return. Esp, in construction, nothing is precise, so being able to eyeball correctly after a quick measurement with a tape and doing some basic math on the numbers, not only accelerates tasks, but is a crucial pillar of being able to work on construction sites, and be productive.
  - ToucanLoucan 2y ago
    I just left a comment on a different thread about detached from reality a lot of tech workers are, and then here I find a guy being like "but rugged calculators are a thing, why do you need to do math in your head?" Tell me you have never built a thing[1] in your entire life that was more complex than an IKEA bookshelf without telling me that challenge: I do hobby projects all the time and I couldn't even tell you how many mental-math problems I do per hour while doing so. It's a LOT. Depending what I'm making I might well spend more time doing math in my head and on paper than I do actually putting tools to materials to build the thing. [1]: by this I mean actually building. With your hands.
    - QuercusMax 2y ago
      I never said you don't need to do math in your head. I said that the argument "calculators are fragile, so you have to do math in your head" doesn't hold water. You're arguing something different, which I tend to agree with.
    - nerdponx 2y ago
      Hell even installing shelves in my closet had me doing trigonometry on a scrap of printer paper to figure out how close I could space together the shelves and still be able to get the boards through the door frame. Calculation is one of the core skills of human cognition and is correspondingly foundational for just about all of human enterprise. Not doing it means limiting your ability to participate in said enterprise.
KeplerBoy 2y ago
What is going on with your tape measures? Confused european over here.
- ein0p 2y ago
  Customary units are given in fractions of an inch. Eg half, quarter, eighth, sixteenth etc. So you’re dealing with simple fractions. That is why I buy tape measures that also have metric scale - to sidestep all that bullshit entirely when adding, multiplying, dividing or subtracting, yet be able to measure distances in inches too
  - ssl-3 2y ago
    I keep a fractional-inch tape measure in the toolbox in my work truck because that's what everyone else (in the US) has, and I need to be able to work with others. I also have to carry around two sets of wrenches, two sets of sockets, two sets of Allen keys, and it's all quite frankly absolute bullshit. But that's the world I get to participate in. At home in my own geeky little workshop, where I don't need to satisfy anyone else's proclivities, everything is exhaustively and exclusively metric-only. My tape measures are metric, my hand tools are metric, my drills are metric, and my fasteners are metric. Working with Freedom Fractions is absolutely forbidden in my workshop (as are all screws with Phillips, JIS, Pozidrive, or Reed-Prince heads, but that's a different rant). And, I must say: It's better this way.
    - nerdponx 2y ago
      > screws Torx?
      - ssl-3 2y ago
        For screws that go into wood (or thereabouts; sheet metal screws can count here too), Robertson is first on my list. The slightly tapered interface fits snugly and tends to hold screws onto a driver bit very well while providing good angular alignment, and it can do all of this without needing magnets. It can also allow for a bit of angular misalignment when necessary, and the chonky squared-off corners and flats resist cam-out/stripping rather well. I'm not even Canadian and I use Robertson wherever I get a chance. Second general choice is hex-head screws. These snap into inexpensive shallow magnetic driver bits with a satisfying click. But they're ugly and kind of rough once installed, and they're not available in flat-head versions. (Hex-head shoulder screws are my only choice for drill-point screws: They maintain positive angular alignment by default and that's crucial for drilling holes in metal.) Torx is fine too, I suppose. I don't have an anti-Torx rule in my workshop, but I try to avoid buying them. They don't tolerate angular misalignment as well as Robertson, and they don't maintain positive angular alignment like a hexagonal shoulder screw does, and they don't stay put with friction like Robertson or snap onto a magnetic driver bit like hex. There's lots of stuff Torx is not very good at doing. Theoretically, I can probably put more torque into Torx than any of the other options listed here, but I don't find that to be a practical advantage in this kind of application: When I can already drive a Robertson screw through a chunk of old-growth wood, I don't need to improve that part. --- For machine screws, I've standardized on stainless steel button-head socket cap screws as a first choice. I've got a deeper selection of them than a good hardware store does, and they're all sorted. (Why stainless instead of graded? Because I don't want them to rot, whether sitting in a bin for decades or used outdoors or whatever and I do not want to stock more than one kind. My fastener collection is crazy enough without also multiplying it by different grades.) There's other stuff, though, too. For instance: Regular socket cap screws have their place -- it just isn't first place. And at the scale of things I build, I mostly use M3, M4, and M5. I buy regular-length Bondhus non-ball hex keys in simple bulk packaging to fit my standard M3, M4, and M5 machine screws. They're very high quality tools, and they're rather inexpensive in bulk. And thus, it is no big deal if I misplace one while I'm working -- I've got more on-hand, and I'm not afraid to get more coming if stock gets low. Bondhus makes a decent-quality hexagonal screwdriver, too, and these are nice to keep around because the design is not like the gigantic T-handled abortions that so many other manufacturers sell: It's just screwdriver-shaped, and it works just like a familiar screwdriver does -- but for socket-cap screws! This was the discovery that allowed me to completely abolish Phillips screws forever from my workshop. I've also got sets of hex keys -- of course I do. Long, ball-end, plain, whatever. I try to avoid cornering myself into a situations where these non-regular variations would ever begin to be useful to begin with, and the long versions are mostly only useful for disassembling stuff that someone else had overtorqued. (But overtorqued fasteners are different rant.)
akira2501 2y ago
> and finding the LCD and GCD of fractions to read a tape measure in US customary units. Well, that's what tolerances are for. I don't need a perfectly accurate answer. Just one that's within 1/32" or more likely 1/4" to 1/8".
- throwway120385 2y ago
  I don't see what tolerances have to do with it? You still have to do math if you have to site a member between two other members regardless of the tolerance. For example, to frame an 8 foot wall you have to cut your studs down to accommodate the top plate and bottom plate and the trim plate above the top plate. Similarly with windows, doors, and headers. Whether you have a 1/16 tolerance or a 1/8 tolerance it doesn't matter. The only time I've had to deal with tolerances when framing is in making sure the drywall doesn't wave anything around by firring out or planing down each stud to put the wall into tolerance.
  - akira2501 2y ago
    The idea that you have to do a full LCD or GCD to work with fractions in engineering or building is not rational.
ssl-3 2y ago
If durability is the chief constraint, and tape measures are adequately durable and already on-hand for the work being performed, then: The tape measure itself can be used to perform basic arithmetic, and will even return results in Freedom Fractions if that's how it is labeled.

AlanYx 2y ago

This isn't just folk wisdom either. There's an active subfield of cognitive science that focuses on working memory/cognitive load and math instruction. Broadly speaking, it's hard for students to successfully transition to even basic algebra if they don't have basic calculations down.

Ntrails 2y ago
That fits with my non expert intuition. If you don't get the basics of arithmetic it is incredibly hard to grasp the idea of "equals" as a pivot point. Division by hand helps to give us a hint that numbers can be broken up into constituents and still be the same. You internalise a whole set of behaviours, typically via repetition, and it unlocks understanding beyond itself imo
abdullahkhalids 2y ago
It's all about building higher and higher abstractions. Arithmetic - > Algebra -> higher order algebraic algorithms. For example, when I taught differential equations, my non-scientific observation was that otherwise smart students struggled more with getting the algorithms down, if they struggled with algebra. Having to constantly jump down to a lower level of abstraction while performing the algorithmic steps is what caused confusion to mistakes.