RPN stands for "Reverse Polish Notation". It was formulated by a Polish mathematician. It is a way to execute functions without using "=", but uses the "Enter" key instead. It actually reduces the no. of keystrokes used. Eg, to compute (3 x 4)/(2+1), the steps are-- 3,ent,4,x,2,ent,1,+,/. The answer "4" appears immediately after pressing the divide / key. Total is 9 keystrokes. Check the above with a Casio algebraic notation calculator and 12 keystrokes are needed! ) [[ I have many HP calculators, including the HP12C, HP15C, HP42s, HP28S, HP48G, HP48GX and HP49G. I am trying to get the first HP calculator HP35. There used to be an International Association of Calculator Collectors, but the guy has shut down the website as well as the club due to work and raising babies. The realities of life!
My first calculator is the National Semiconductor's Novus Mathematician. ( Picture here ). It is a RPN calculator. I bought it in 1976 when I studied Engineering in the University of Singapore. It cost me about US$60 a big amount to a poor student, but of course still cheaper than the dream HP calculator. I like to use RPN. That explains why I now "collect" HP calculators. The 1st electrionic calculator in the world is the HP35. Here's a picture of it.
Calculator as Tally Counter
We usually use a 4 function calculator. The ideal calculator for normal use is a 7 function type. The 7 functions are : +,-,x,/, sq root, reciprocal & square. Most functions including trigonometric may be performed efficiently with a 7 function calculator. Unfortunately, no one makes it. I collect calculators. If you have an old one - or a 7 function one - please give it to me, OK ? < ** Latest News -- I have found the Texas Instruments "Maths Explorer". It has the 7 functions I am looking for. It costs S$10.00 at a shop in Rochor Complex.-- 9 May 99 > **
You can also use a simple 4 function calculator as a tally counter to count the no. of people passing by, for example. How to use? Assuming you are counting 1 object at a time- key 1 in your calculator, press + , press = sign to start counting. If you press = 5 time, the display will show 5. To count in pairs, key 2, press +, start counting by pressing the = sign.
Usage of Calculator in Supermarket?
Can my simple four function calculator do chain addition of multication. This is a very common problems in the supermarket and your simple calculator can help you a lot to keep track of expenditure before you pay up at the cashier....Eg, I buy 24 apples at $0.15 each, 13 oranges at $0.30 each, 2.3 kg of kangkong at $0.77 per kg, 2 packets of milk at $1.55, 3 loaves of bread at $1.80. Heh heh, but your simple calculator do not have memory storage, no () brackets? No problem. Remember what you learn in Jr School all those years ago? Factoring? Eg, (3x2)+(4x9) = [ (3x2)/9 + 4 ] x 9 ??? This is real easy to compute but the answer is 41.999999. The actual answer is 42 exactly. But what about the supermarket problem above? Tell me how you are going to operate your simple four function calculator. I complete it in under 2 minutes and the answer is $17.77.
Other Ramblings
A simple 4 function calculator ( +, -, x and / ) without memory can be used to calculate square root of a number easily using the Newton-Raphson iteration. Of course if memory storage is present the job is easier.
The simple 4 function calculator can also be used to compute trigonometric functions like sine, cosine, using some sort of series expansion. I used to be able to do this rather quickly on a simple calculator! You need to use a rapidly convergent series expansion. I will write more on this next time. Why do all these when a scientific calculator is available? Just for fun and for the day when scientific calcs are lost to the world...
Here is a picture of a 7 function calculator from Texas Instruments.
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