Who uses scientific calculators?

[Mark44]

Yeah, this is kind of what I was thinking. I believe that mechanical devices like slide rules and abucuses (abaci? I don't know the plural) can really help mathematical intuition.

Yes, abaci is the correct plural, which I believe is pronounced ab' a see.
Working with a slide rule can help with mathematical intuition because you have to figure out the correct power of ten for many calculations, such as 432 x 363. The way it works is that you put the 1 marker on the C scale on, say, 4.32 on the D scale, and then slide the cursor to 3.63 on the C scale.(In doing this I actually had to put the 1 marker at the right end of the C scale on 4.32). On the D scale, the cursor shows a little shy of 1.57. Since 432 is really 4.32 X 10² and 363 is really 3.63 X 10², my slide rule answer is 15.7 X 10⁴, or 1.57 X 10⁵. This isn't too far from the exact answer, 156,816.

How a slide rule works for multiplication can give one a good insight to logarithms, as many of the scales are laid out logarithmically. The 1 on the left end of the C and D scales represents 0 (the log₁₀ 1 is 0). The 1 on the right end of these scales represents 10 (whose log is 1). The 2 on these scales is placed about .3010 of the way between the two ends, and 3 is placed about .4771 of the way.

When you multiply 2 and 3, you are really adding the logs of these numbers, and getting the log (base 10) of the answer. For example, placing the left-end 1 of the C scale on the 3 of the D scale, and then moving the cursor to the 2 on the C scale lines up with the 6 marker on the D scale. In effect you are doing this addition: $\log 3 + \log 2 = \log(3 \cdot 2) = \log 6$.

Division is just the opposite; instead of adding the lengths (adding the logs), you subtract the lengths.To calculate 3/2, put the 3 on the C scale above the 2 on the D scale, and read the answer on the D scale under the 1 on the C scale. You are effectively subtracting the length of 2 (on the C scale) from the length of 3 (on the D scale) to get the quotient, keeping in mind that what I'm referring to as "lengths" are really logarithms in base-10.

 

[dkotschessaa]

Yes, abaci is the correct plural, which I believe is pronounced ab' a see.
Working with a slide rule can help with mathematical intuition because you have to figure out the correct power of ten for many calculations, such as 432 x 363. The way it works is that you put the 1 marker on the C scale on, say, 4.32 on the D scale, and then slide the cursor to 3.63 on the C scale.(In doing this I actually had to put the 1 marker at the right end of the C scale on 4.32). On the D scale, the cursor shows a little shy of 1.57. Since 432 is really 4.32 X 10² and 363 is really 3.63 X 10², my slide rule answer is 15.7 X 10⁴, or 1.57 X 10⁵. This isn't too far from the exact answer, 156,816.

How a slide rule works for multiplication can give one a good insight to logarithms, as many of the scales are laid out logarithmically. The 1 on the left end of the C and D scales represents 0 (the log₁₀ 1 is 0). The 1 on the right end of these scales represents 10 (whose log is 1). The 2 on these scales is placed about .3010 of the way between the two ends, and 3 is placed about .4771 of the way.

When you multiply 2 and 3, you are really adding the logs of these numbers, and getting the log (base 10) of the answer. For example, placing the left-end 1 of the C scale on the 3 of the D scale, and then moving the cursor to the 2 on the C scale lines up with the 6 marker on the D scale. In effect you are doing this addition: $\log 3 + \log 2 = \log(3 \cdot 2) = \log 6$.

Division is just the opposite; instead of adding the lengths (adding the logs), you subtract the lengths.To calculate 3/2, put the 3 on the C scale above the 2 on the D scale, and read the answer on the D scale under the 1 on the C scale. You are effectively subtracting the length of 2 (on the C scale) from the length of 3 (on the D scale) to get the quotient, keeping in mind that what I'm referring to as "lengths" are really logarithms in base-10.

Thanks for this. When I get a moment I'm going to mess with the one I have.

 

[Mark44]

Thanks for this. When I get a moment I'm going to mess with the one I have.

I have four of them: a very cheap plastic one with scales on only one side and blank on the other; a plastic one that must have been a bit more expensive, with scales on both sides; an inexpensive aluminum one with scales on one side and fraction-to-decimal conversions and other stuff on the other side; a very nice bamboo slide rule with a leather case and a magnifying lens, and scales on both sides. This last one belonged to my wife's father. He must have gotten it back in the '30s or so.

 

[Robert Sanchez]

I inherited one from my dad and I really want to learn how to use it. I always thought it would help me intuitively understand logarithms a bit more.

-Dave K

I recently purchased two slide rules from ebay. sliderulemuseum.com has step by step instructions for basic use.
My older sister used one in high school and by the time I got there, TI calculators were in the classroom.

As for calculator use now, I have a HP48GX that I've used for the past 18 years and it's the only device I know... I love RPN.

 

[litup]

In my job I use a casio fx 300ES and the like for general math stuff but I use the time function almost every day. I have machine runs that takes 5 or 6 hours and the operators need to know when it will finish the run so I have to use the machine scan speed and calculate the run time so hour minute and second notation is crucial and it works well. I have a 12c also, trying to learn RPN programming and an HP48 but I seldom need that much caclulator, lot of conversions and such, pounds to grams, F to C, that kind of thing, and constants like c and G and such.

 

[levadny]

Who uses scientific calculators, aside from students and teachers? Engineers and physicists, I suppose.

I am software engineer. I use standart windows calculator, but my collegues use scientific calc develop in our company in Delphi.