#### YoungPhysicist

Summary: A short introduction to a antique calculator that I recently got

I first know about this thing when I was chatting with @jedishrfu a couple months ago, and I was fascinated by it. It functions like a soroban but looks way cooler and easier to carry around. Also, it is a important calculation tool before digital calculators exist.

So, I finally decided to buy one:

It works by sliding the middle bars with a stylo(the pen like thing) thus showing numbers from the center hole. It uses a clever mechanism to carry the digits from one row to another: You slide the stylo over the hook shape grove on top of every row and push the next row by a single digit.

Because mine is not in top condition and the sliding is quite stiff, but it is still functional and still amazes me. Although it's function has long been replaced by digital calculators, it's still a important artifact in the math history.

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#### jedishrfu

Mentor
What else is cool is that there are very few moving parts and the only user failure mode is to not follow through during the carry at the top vs all the myriad ways circuits can fail in a calculator.

This is a great piece of nostalgia from a simpler time free of computers.

Thanks for sharing.

#### YoungPhysicist

Thanks for sharing.
Thanks you for sharing, too!

#### fresh_42

Mentor
2018 Award
What else is cool is that there are very few moving parts and the only user failure mode is to not follow through during the carry at the top vs all the myriad ways circuits can fail in a calculator.

This is a great piece of nostalgia from a simpler time free of computers.

Thanks for sharing.

#### jedishrfu

Mentor
What was bad about them other than you couldn't use them in school?

#### fresh_42

Mentor
2018 Award
What was bad about them other than you couldn't use them in school?
Let me put it this way.

Once on a warm summer evening after work, I stood in a cocktail bar with someone about my age. It was a time in the 90s when they covered many old songs from the 70s. To most people they were new, but of course my neighbor and I could sing along all of them, which we did in a way (for us, not for the entire bar). Suddenly he poked me and said: "You have to be cautious nowadays what you sing." Still caught in the old tune I asked why. "Well," he answered, "it tells how old you are."

#### DaveC426913

Gold Member
Had one of these in my childhood.

#### jedishrfu

Mentor
Just tell them you're older than dirt and they will be impressed at how young you look.

#### anorlunda

Mentor
Gold Member
Ah yes, I remember them too. That dates me.

Even more fun from that era, was this calculator from Curta. You could hold it above your head and swing it around in circles to "crank out the answer."

It was my belief that Facit made a hand calculator similar to the Curta and that was the origin of the idiom in Swedish. For example, "Med facit i handen skulle vi ha gjort annorlunda" meaning "In retrospect, we would have done it differently."
But I can't find any supporting evidence for that. Perhaps @mfb or @Doc Al can set me straight.

#### Doc Al

Mentor
Don't look at me! That's some pretty cool stuff, but I don't know anything about it. (Though I admit to being ancient. ) The only "mechanical" calculator I've used was my trusty slide rule, replaced by my shiny new TI SR calculator (SR 10/11, I think).

#### fresh_42

Mentor
2018 Award
The slide rule had a big, big advantage, which I sometimes have the feeling got lost: You had to do a separate calculation for the magnitude of the solution! I wished kids nowadays would also had to do it.

#### DaveE

The slide rule had a big, big advantage, which I sometimes have the feeling got lost: You had to do a separate calculation for the magnitude of the solution! I wished kids nowadays would also had to do it.
Absolutely! It also taught you the real meaning of significant digits. I'm not sure how many people today realize that π = 3.14 is really good enough, almost always. For accuracy π = 3.1416. More digits than that usually just demonstrates your ignorance of engineering.

#### DaveC426913

Gold Member
I am a hair too young for slide rules.

#### YoungPhysicist

Hmm, it appears that I am the only one in this thread that don’t have stories from the past...... Not surprising.

When I was born, digital calculators had took over for a while, and the only mechanical calculator that is still lurking around is soroban(which I think will still be lurking around for years to come).

This just shows how young I am.

#### Klystron

Gold Member
The slide rule had a big, big advantage, which I sometimes have the feeling got lost: You had to do a separate calculation for the magnitude of the solution! I wished kids nowadays would also had to do it.
Absolutely! It also taught you the real meaning of significant digits. I'm not sure how many people today realize that π = 3.14 is really good enough, almost always. For accuracy π = 3.1416. More digits than that usually just demonstrates your ignorance of engineering.
I am just old enough to have learned how to use a slide rule as a child. The coolest thing for me along with the above was learning logarithms. I was so young I created my own names. I called the base of natural logarithms "Eee" and the inverse function "Lenny".

Seldom used my slide rule for calculation. If I could not figure it in my head, my mother the librarian had an electro-mechanical calculator that printed on a paper strip.

#### jedishrfu

Mentor
As i read the electro mechanical part, I imagined your mom was going to apply electroshock therapy on your head aka tiger mom.

#### fresh_42

Mentor
2018 Award
I called the base of natural logarithms "Eee" and the inverse function "Lenny".
I had a similar thing going on with logarithms. I observed that addition $\longrightarrow$ multiplication $\longrightarrow$ powers $\longrightarrow$ etc. built natural extensions. So I thought about a binary operation $\circ$ such that there is another one on the left end of the chain $\log (a+b)= \log a \circ \log b$. My only condition was, that $2 \circ 2 = 4$ must hold, since $2+2=2\cdot 2= 2^2 = 4$.

#### jedishrfu

Mentor
For the exponents part, I developed a simple rule ie add the factor exponents on a multiplication and if the right index was used to point to a factor add 1 to the exponents.

I usually wrote my numbers in scientific notation too.

The funny part was while it sped my calculations along my teacher didn’t like the rule. He wanted kids to “realize” the answer needed a factor of ten as in knowing that 3 x 4 is 12 and not 1.2

Whereas I would say 3E0 x 4E0 is 1.2E0 but then added one to get 1.2E1 or 12 because i used the right index on the C scale.

#### jedishrfu

Mentor
With respect to the Curta, Scientific American did a story on it calling it a pepper-mill because of its looks.

Also i heard you never ever take one apart because youll never get it back together.

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#### jedishrfu

Mentor
Woth respect to PI, many sliderules had a special mark on the scale that was a bit more accurate than using 3.14. Similarly for the mysterious e number and for r radians.

Also some rules had a separate C prime and or D prime scale which had pi factored in saving one multiplication step.

#### jedishrfu

Mentor
With respect to the addiator, I wondered if using it in combination with Trachtenberg rules of multiplication allowed it to effectively do multiplications quickly. The one problem with Trachtenberg was the need to keep multiple rules in play as you processed a multi digit calculation like 3141592 x 271834 which some kids could do on a blackboard in one line at blinding speed.

#### fresh_42

Mentor
2018 Award
Woth respect to PI, many sliderules had a special mark on the scale that was a bit more accurate than using 3.14. Similarly for the mysterious e number and for r radians.
You made me fetch that darn thing!

Mine has 11 scales on each side. Unbelievable! And meanwhile I have another problem: Some of those scales are so tiny ... and my eyesight meanwhile ... But, it still works! I'm not sure similar can be said about electronic devices after so many years.

#### YoungPhysicist

With respect to the addiator, I wondered if using it in combination with Trachtenberg rules of multiplication allowed it to effectively do multiplications quickly. The one problem with Trachtenberg was the need to keep multiple rules in play as you processed a multi digit calculation like 3141592 x 271834 which some kids could do on a blackboard in one line at blinding speed.
Probably, but a good hardware is essential.....

#### jedishrfu

Mentor
You can always apply a steampunk solution using a magnifying lens attached to the sliderule ala the Brazil movie computer terminal scene.

#### gmax137

search u-tube for "addiator" -- there are a few nice short videos demonstrating use.

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