Math without Tech - Reject Calculators Return to SlideRules

[Duiker]

We can all do at least some math in our head, but if you don't have a computer, phone, or calculator on hand, and need to crunch something complex, how would you do it? lets discuss various methods and tools to do calculations, preferably in a context where electricity wasn't readily accessible. This includes any interesting math tricks others may find useful.

Abacus

It's one of the oldest tools for this purpose and are still taught in schools to this day. I prefer an japanese style called a soroban. You can add, subtract, divide and multiply (although division always feels a bit finiky)

A guide on how to use it.


Sliderulers
With just two pieces of wood sliding against each other you can do some impressive calculations, although paradoxically it's not suited for addition or subtraction. Once you learn how to use it, it can be surprising how quickly you can get answers to equations.
An old timy tutorial on how to use one.

Analog Calculator
There was a time from between the 1920s to about the 1980s where pocketsized mechanical calculators were possible that used sliding plates to do addition and subtraction. You can still find them being sold on ebay.
The slide calculator

 

[Aero the Alcoholic Bat]

They still teach kids how to work out math problems on paper, right?

 

[Duiker]

They still teach kids how to work out math problems on paper, right?

true, and I bet some folks have tricks with that I don't know either.

 

[Grim_Autismo]

Math is a fun hobby, and a while back, I wondered how they were doing complex matrices before we had computers or even personal calculators in the late 60s/early 70s. (those earlier "personal calculators" don't count; they were enormous and didn't use solid state/integrated circuits until the 60s, so weren't handheld/portable)

Meet Classical Matrix Algebra, calculating Eigenvalues as they did 100 years ago and beyond. Fucking wild. From Modern Algebra and Matrices, 1951

They were just manually transforming everything and checking to ensure everything was correct manually. We don't consider the amount of math we outsource to computers today and how much of what we learn now has been simplified; past curriculums are fucking insane to take a look at.

We built the atomic bomb and the first computers with this kind of math. It's amazing!

 

[Procrastinhater]

What do you guys think about shake n ba... oh sorry I thought it said Meth without tech...

 

[Cirrhosis_of_Liver]

If God meant me to understand quantities last 12, he wouldn't have given me shoes.

 

[Doctor Love]

You can use a type of woodworking measure for finding the centre point of shit, and you can use a compass to work from an "arbitrary" base.

I base measurements off of paper sizes, so I can just print off an A4 sheet with an extrusion shape and cut around it.

 

[Safir]

Meet Classical Matrix Algebra, calculating Eigenvalues as they did 100 years ago and beyond. Fucking wild. From Modern Algebra and Matrices, 1951

...wait, this isn't taught in US universities? We learned this in linear algebra in 2003 and I'm 140% sure it's still in the curriculum.

 

[Doctor Love]

For hand tools - compasses are fantastic for shapes in general. You can use logic to figure out an angle by continually halving the compasses' length.

A circle is 360, 90 for each quadrant - just keep halving it, or start from base-3 with a triangle, and you can add/subtract as needed.

Worth it for hexagons and perfect equilaterals.

 

[Grim_Autismo]

...wait, this isn't taught in US universities? We learned this in linear algebra in 2003 and I'm 140% sure it's still in the curriculum.

Linear Algebra is still a class, but it's a second year/sophomore class (if it's offered at all, sometimes not.) I know several people who only have one or two math classes and don't even get anywhere near linear algebra for their degree. A lot of people entering college can't even do HS math. Shit's getting pretty scuffed these days.

One of the major issues, if you're in the US in many places, is that you have to wait until after Calc 2 to take Linear Algebra. Which is bullshit; you really don't need Calc 2 to take Linear Algebra. But here's a really cool article by a professor about how math changed in the US, and especially how standards in algebra changed.

We still learn how to calculate matrixes, but they're generally pretty dumbed down compared to what you'd find in books from 1900-1960. Check out the Internet Archive. The old math books are heavier on theory, whereas newer math books are heavier on function. They're concerned with explaining WHY a thing does what it does, not just drilling into you specific tricks, because you couldn't just run to Google to check your work if you fuck it up.

 

[Jeff_the_Thriller]

I worked as a low voltage controls electrician in a previous job. The end user saw a motor or valve at 0 to 100% on a screen. A microprocessor board doesn't know what a % is so this would translate to an electrical signal in voltage or current. This was a basic slope intercept formula (y=mx+b). We had a computer calculate the values to put in the board. If I was bored at work I would do the calculations by hand doing y=mx+b substitutions just show off my skills at 9th grade math. I'm kind of surprised at the amount of people that can't do simple math with just pencil and paper.

 

[The Mass Shooter Ron Soye]

Try a solar-powered calculator. Hey, why can't I see the Sun?

 

[High Level Rad Waste]

...wait, this isn't taught in US universities? We learned this in linear algebra in 2003 and I'm 140% sure it's still in the curriculum.

It's not. Even in calc, it's about how to use a graphing calculator.

 

[torpig xmr]

I use regular printing paper but this is something I would love

https://en.m.wikipedia.org/wiki/Kraft_paper

 

[Seija Kijin]

Any advice on getting better at math when you also have dyscalculia? I struggle with math, but I’d love to become more proficient without relying on tech as much as I have to.

 

[The Real Slim Shady]

Anything in math that doesn't involve arithmetics. Apart from arithmetics which is about calculations (summation, division etc.), in pure mathematics you rarely see large numbers. Even in a college algebra book it's hard to find a number larger than 10.

 

[Kiska]

As far as all-mechanical machines go my favorite calculator/adding machine is still by far the Curta. It's one of those things I want but never want to bother with paying the collector consoomer tax since they frequently sell for thousands when in working order. Honestly would wish someone reverse engineered them in the modern day since it's really pocketable and convenient to use machine that relies on 0 electronics.

Try a solar-powered calculator. Hey, why can't I see the Sun?

Fun fact many "solar-powered" calculators are so cheap they use fake solar cells, the cell is usually just a plastic piece or decal and the calculator is actually powered by a button cell battery.

 

[The Real Slim Shady]

Honestly would wish someone reverse engineered them in the modern day since it's really pocketable and convenient to use machine that relies on 0 electronics.

As far as I can tell the mechanism is known and reverse engineered. The price is high because (apart from being a niche of a niche) the mechanisms are very small and complex. The tolerances are very tight too, so it needs specific grade of materials. This is also the reason why 3D-printed clones are the size of a large bucket because its not possible to reliably 3D-print elements that small with such precision on a random 3D printer.

ETA: also, unless you need so much numerical precision, a good 12 inch slide rule is more than enough for everyday calculations

 

[Kiska]

This is also the reason why 3D-printed clones are the size of a large bucket because its not possible to reliably 3D-print elements that small with such precision on a random 3D printer.

Should've been more specific and said it to being in a pocketable degree since I'm pretty sure I've seen those 3d printed mechanism remakes too, and yea it's quite a niche item since I can just calculate most everyday things in my head or by hand but it's a level of item that's a "nice to have" like a cool mechanical watch. I do know the all-mechanical desk top adding machines are still a good bit cheaper since they're a lot more plentiful and relied on more simpler mechs.

 

[Carlos Thin]

http://mcb111.org/w01/Mathematical_Handbook_of_Formulas_and_Ta.pdf

Basically just keep the math and physics books you had in school. Simply reading through them without the stress of exams or homework will make for wholly beneficial reading