I see a lot of wrong info on the the decimal slider. This is how it works:

A is for "Add-mode". This means that 2 decimals are always assumed. It's used for adding a lot of 2 decimal numbers, because you'll never have to press the decimal key. If you've ever worked a credit card terminal and having to enter 200 to get 2.00$, that's how this setting works.

0-6 are fixed and rounded according to the rounding setting.

The decimal F is for floating. It'll use the most relevant amount of decimals.

Another funny button is MU which is Mark Up. It's used with the percentage button. It's a backward ass way to do percentages. You'll enter a value and then MU the percentage that you want from the result, instead of the input. Say you have product that costs 100 and you'll want to mark it up, so you'll get 20% of your new sales price as profit. Press 100 MU 20% and it should show 125, which is your sales price, because 25 is the 20% of 125. It doesn't make sense to me why anyone ever needed that button.

The first one lets you turn K on or off

Found some documentation listing the two middle switches as the rounding switch (up fraction down) and the decimal switch (auto? 0 to 6 then hex?). No idea on the other two.

http://www.calcuseum.com/SCRAPBOOK/BONUS/32853/1.htm

Decimal switch: [A-0-2-3-4-6-F], Round switch: [(ArrowUp)-5/4-(ArrowDown)], Miscellaneous switch: [(Blank)-K .-(Sigma)],

Some guesses by ChatGPT:

Left Switch ("K" setting):

• K: Likely for a "constant mode," where the calculator uses one operand as a constant for repeated >calculations (e.g., multiplying several numbers by the same value).
• The other position is likely "normal mode," disabling this feature.

Middle Switch ("A/2/4/6" etc.):

• This could control decimal rounding or precision:
• "A" might stand for "automatic" mode.
• "0, 2, 3, 4, 6" refers to the number of decimal places displayed or used in calculations.
• "F" likely stands for "full precision," using all available decimal places.

Right Switch ("Σ" setting):

• Σ: Likely enables a "summation mode," where the calculator automatically adds results to a running total (useful for bookkeeping or repetitive additions).
• The other position disables this mode.

Being Swedish the "constant mode" seems likely as we often used k (for "konstant") in school math to represent a constant (e.g. for the slope of a line).

No.

Looks like Facit calculators were originally manufactured in Sweden and then later Japan. No mention of that particular model on this website, however

Well, I see a round up, didn't round, or round down switch. The next one might be how many points if precision??. The last one has to do with sum vs series somehow.

That is interesting, though. Beyond me, that's for sure

They seem to have some kind of function regarding how to perform or display calculations.