 This is a computer. Or at least back in the 1930s, 40s and 50s, the person operating it was a computer. You see, back then a fully automatic calculator like this one was mind blowing, allowing people to add, subtract, multiply and divide large numbers without the use of pen and paper. These days that's all done electronically, but when Richard, a local fan, reached out and said, hey, I've got one of these, we jumped at the chance to become the very thing we love the most, computers. Thanks to SignalRGB for sponsoring this video. SignalRGB is a free application that syncs RGB lighting across your entire setup and works for brands like Corsair, Razer, Logitech and more. Check it out at the link down below. When I was in school, teachers would insist we learn to do long division by hand because you're not going to be going around carrying a calculator everywhere you go. Well jokes on you, Miss Parsons, because now everyone is doing exactly that. And trust me, this baby does long division. But back in the nineties, Miss Parsons could be forgiven for thinking that pocket calculators wouldn't be as ubiquitous today. Seeing as many older folks back then may have grown up with something a lot more like this, the Frieden STW10. If we were to go back another 30 years, there's a good chance we'd find one of these chunky boys on an accountant's desk. In fact, you may have already seen something like this either online or in a stirring historical drama like Hidden Figures. No, it's not a typewriter, although it does sort of share some similarities. There's a sliding carriage on top and a large set of keys on the body, but these are all numbers and there's no ink or paper needed. At least not any that you insert into the machine itself. The first set of mechanical number displays on the carriage is the accumulator row, which can display results up to 20 digits long. For reference, most pocket calculators today only display around 8 or 10 and my phone can interrupt to 15 digits before it starts using exponents. The row below that is the counter register. It serves a couple of different functions, just like how our new indoor sweater from LTTstore.com keeps you warm and boosts your confidence. Don't quote me on that. The first function is how it acts as an item counter when adding or subtracting. And the second is operations counting when multiplying or dividing. You can lock these rows or clear them with some button presses. Or you can use one of these guys down here to set where the decimal starts for division. I want to start it there. Now down here, one numpad would be Bush League. So we got two. This little one over here is used only for entering multiplicands, more on that later. And the big one is used for everything else. Each digit has its own column and you enter your total value by pushing down keys as they would appear on paper. So for example, for 1337, we push them in order like this. If any column has nothing pressed, that counts as zero. It's a little confusing at first, but you get used to it pretty quickly. Everything is housed in a shell made of what we think is aluminum covered in plastic. That's pretty easy to take off. And there's a giant pad of foam underneath to keep this mechanical beast from shaking your table to death. I mean, this thing is heavy. Oh, I'm doing math. I feel smarter. You can see on the inside, it's basically a giant mishmash of gears, levers, springs and arms. It's like mechanical spaghetti in there. It is incredibly complex. And the amount of engineering that went into something like this is absolutely insane. There were earlier models like the 1941 Frieden H8, but these were often limited to addition and subtraction and weren't driven electronically. The STW-10 came out a few years later and gave simple computers, like us, the ability to multiply and divide big numbers easily. Hey, what do you say we crunch some numbers? So to add, you enter a value on the main pad and add it to the top row like this. Bam. Now we enter whatever number we want to add to that number by entering new values and pressing the add button again. So what it's actually doing is setting a value on a number of dials and then ticking everything up by the new value in sequence. It's a lot like how you would do paper math, adding each digit until there's an overflow, then adding the overflow to the end. If we want to subtract, it's basically doing the exact opposite by starting with a value and then decreasing it in sequential order by the new value. Multiplication works in a similar way. It's basically just addition in groups, except this time we get to use the cool multiplicand numpad. I've been waiting so long. This one actually works like what you'd see in a modern calculator where you enter each digit serially from left to right and it brings up your value on this little display here. Next, we enter our multiplier on the big numpad, press the malt key and look at it go. That is so cool. We'll get some slow-mo footage, but as it's going, you can basically watch it in real time working through the numbers, brute forcing addition of our multiplicand as many times as I've told it to because again, I am the computer. Division is basically the same thing, but backwards like subtraction. Enter your first number on the big keypad, set your decimal place and hit enter divd. This puts the carriage to where it needs to go according to our decimal point. Clear the keyboard if it didn't automatically and enter your divisor on the same keypad. Now we're going to have to hit both of these divide keys. We'll get to why there are two in a moment, but for now, look at it go. Man, that never gets old. Just like hitting that subscribe button never gets old. We've got our eyes on an antique kith or a mechanism video in the future that you don't want to miss. Now for the most part, this should just work. It crunched through the numbers to the nearest decimal point and gives us our result, which is a, give me a sec, 33.3 repeating of course. But if you were to accidentally divide a number by zero, the machine can get stuck in an infinite loop. What? Back in the forties and fifties, if a room of accountants or something was using automatic calculators without this handy div stop function we have right here, there'd actually be a guy in the room whose job it was to basically just listen for this infinite loop and walk around resetting machines. Now this bad boy is pretty well lubed. Thanks to Richard. Did you lube it up? Oh yeah. Oh yeah. But rapidly moving metal moving for a long time gets really hot. So if there was no button or no button, man, you'd find out what was at the end of that infinite loop. Molten destruction. At this moment, you're probably screaming at me at the top of your lungs. Riley, why does this have two division buttons? Why? I'm going to need you to calm down. By the time division and multiplication were added, someone else had already beaten Frieden to the punch and patented a single button division system, preventing Frieden from including it in this model. If you press only the left division button, the division will take place, but you'll get only the tens compliment of the expected result. Now the STW 10 was only designed to do addition, subtraction, multiplication and division, but some masters of the universe actually figured out how to get square roots on this thing. How you ask wizardry. Dine in. So in order to actually do a square root on a calculator like this, you have to follow a number of different types of algorithms to actually do it. These machines don't have a push square root button, but math has developed algorithms that you can use to quickly calculate a square root on a machine like this or on paper or anywhere else. For this machine, the algorithm that we're looking at using is the sum of odd squares. For our sake, it works. I'll take you through the steps of how it works for this 69 420. First up, you move your carriage all the way over and make sure that it's aligned with the 10th digit of your number. Then you enter plus five times. Now clear off and move the carriage all the way over. Now we'll go through and actually get into the weeds of calculating this number out. You put a five in the next column over. This is the column we're actually calculating one and you start subtracting away. As we're going through each increment, we're essentially adding another one of the odd numbers through some math magic. But as we're subtracting away, one, two, that's when you know that's the number you're looking for. You add it back, shift the carriage over one, shift the five over one and start again. And this is where it starts getting a little bit repetitive, but it works. There's another underflow, add it back, clear the five, move it over, shift the carriage and again. Underflow, add it back, clear the five, move it over, shift the carriage. And subtract. Their underflow, add it back and repeat. In this particular algorithm, we're breaking it up by individual digit, similar to like what you do on paper. So we're starting with the biggest number and slowly shifting our way down as we move on. And that's an easier way to try to handle numbers that are five plus digits long, especially for a square root. Now that we're on this last line, we can't move the five over anymore, but we just clear it off, shift over the carriage and do the same step again, just without the extra five. And now we've done the square root. But where's the answer? We have a whole bunch of different numbers on the board. For this, it's actually the board itself. We have two, six, three, point, four, seven, six, seven, five, four, one. So this kind of shows the power of, you know, interesting approaches to trying to solve calculations that used to take minutes, hours, days in an order of magnitude less time. I'd have to learn how to do it on pen and paper first. So what happened to calculators like this? Well, Frieden sold thousands of these things primarily to accounting and insurance companies and then ended production of the STW-10 in 1966 as the EC-130, a transistor calculator with a 13 digit capacity, started taking over. Frieden was bought out by Singer, known primarily for their sewing machines at the time, and eventually died off in the 70s as pocket calculators like this one hit the market. I mean, as awesome as this absolute unit is, it's pretty obvious why these started winning out. So let's do 8,872 multiplied by 4,307 and go! Yeah, sorry, Frieden. Still love ya. If you want to try and buy one of these and try and restore it yourself, they seem to go from anywhere between two and $500 if you can find one. You'll also be lucky if yours arrives in perfectly working condition. If you want any tips on restoring or using them, make sure to check out Richard on Twitch, twitch.tv slash Scrobotosaurus. We'll have that as well as any affiliate links down below. Thanks to Bessie Footwear for sponsoring today's video. Bessie Footwear is known for being lightweight, easy to pack, comfortable, and most importantly, water resistant. Designed to keep you moving, Bessie released their new everyday move shoes. They've got enhanced breathability and added support, making the style perfect for the adventurous or those looking for something sportier. 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