What calc for my 7 years old son?

He's just started to do additions, and he finds nice playing with numbers.

We all know RPN's better, but... would you have your son endure all you have endured? (unability to properly use other calculators, he cannot lend his to other lads, freak factor...)

And if so, which one? (I have gone from 33c to 17bII, 19bII, 41 (cv & cx), 42s, 48gx...where I am keeping all except the 33c - which broke 28 years ago...)


Jose, there is no better topic guarateed to raise a ruckus on this forum than this one!

For a kid just starting first or second grade (7 years old), as a teacher, I would recommend NO calculator. Let him learn the basics with pencil and paper and understand the principles behind the math first. By the time he hits middle school, if he knows these basics, and if he has supportive parents and good teachers, he will do just fine without a calculator at all. But there are good calculators to enhace the middle school math student's experience, such as the TI34 Multiview (or HP SmartCalc 300s). I teach middle school math, and after my students demonstrate that they can do the calculations with pencil and paper, I let them use a calculator. And they frequently discover insights they didn't know before by doing that, so I think it is valuable.

Don Shepherd


For a kid just starting first or second grade (7 years old), as a teacher, I would recommend NO calculator. Let him learn the basics with pencil and paper and understand the principles behind the math first.
+1. It would be a big disservice to him to give him a calculator.


I am a teacher for more than 15 years, and although being a university teacher, I had some experiences with the equivalent to the US high school here in Brazil. We call it Medium or Secondary Teaching (9 years, now) because it is between the Fundamental Teaching (first 4 years) and the University. I also have a daughter that has not a single interest in math nor in calculators (I do that for both of us...).

Fact is that I second Don´s and Garth´s thoughts. Calculators should not be used to build math skills because they are actually the next step after the abstract math reasoning has already been built. I tell my students that math has many related areas, and calculating is just one of them that actually permeates almost all of the others. It is only a tool for the means of giving reason its magnitude. It is such that way that even a machine can do that. But most of all, understanding the meaning of the numbers is more important than getting to the numbers (calculators get to any numbers, we must be the ones to know what to do with them). When a calculator is a curiosity, people just press the buttons for the sake of the 'what...if's. When it becomes a tool, it will be used only when needed. Nobody messes up with tools, whichever they are.

Consider the following: allow your kid the access to a calculator when his reasoning looses track while he is crunching the numbers.


Luiz (Brazil)

Edited: 26 Oct 2009, 7:23 p.m.


Apart from the "should he even have a calculator" debate, the answer is simple, RPN is just silly and archaic.

They learn and write "1 + 1 =" so a calculator should be expected to work the same way.

Forcing him to use a calculator that requires "1 ENTER 2 +" is just silly IMO. Show him RPN at a later date by all means, but don't start him off on it, there are more important things to be confronted with with and investigate at their age.

Flame away :-P



He's just started to do additions, and he finds nice playing with numbers.

Get him an abacus. No joke. Learn it together.

Other things to consider: A bag of dice, dominos, etc... stuff you can count. Then move to probability. Everybody loves probability.


Agree, Dave.

RPN might be a good topic in a graduate course in arithmetic entry systems in general, for those who might be interested in its capabilities, but apart from exceptional circumstances, I can't recommend its use in elementary or secondary education.


Forcing him to use a calculator that requires "1 ENTER 2 +" is just silly IMO.
It is well known that Algebraic Notation and Reverse Polish Notation are, as their names say, notations, and not expressions. When one reads
1 + 2
and thinks of
it does not mean a sign of 'equal to' is demanded somehow, somewhere. And when one writes
+ 2
it does not mean a '=' is missing somewhere to finish the calculation. If we write '1 + 2' and say 'is equal to', then we do not need to add a '=' sign.

Considering RPN a silly notation is considering the closest notation to what one writes in a paper to perform a handwritten calculation silly, too. When we add, multiply, divide, compute a square root or whatever calculus that can be performed with paper and pencil, not one single time a '=' is needed. It can be used, mostly to indicate an answer, but it is not needed to perform calculations.

When we are writing down equations then it is another story, '=' is used to separate left and right sides of it. But we are talking about calculators, number crunching, not expression evaluation. RPN and Algebraic Notation live together in many new HP calculators, it is just a matter of what one wants to do.

And yes, Hewlett-Packard designers took advantage of the natural assembly language coding, which is closer to the actual calculations themselves, where adding A to B is expressed with the mnemonics

add A,B
and again, no '=' is demanded. Allowing A and B to be available and located prior to add them is the key for RPN operation, so [+] means
add Y,X.
Maybe my point is too focused, but I actually began reasoning and solving problems better after reasoning in RPN-fashion. I still do today, and this is due to RPN existence and a notation. I never dealt well with Algebraic Notation and I believe because it is not too close to the actual calculations, and my first calculator was a TI57 (1980, still with me). My second one, an HP41C (1982, still with me, too) actually helped me a lot more.



Edited: 26 Oct 2009, 8:40 p.m.




In a few years, when he gets to algebra and starts learning about logarithms, get him a slide rule. Seriously. It's a great way to "see" how logs work.

With my kids, they didn't get a calculator until it was required for a particular class....about age 13 or so IIRC. However, starting about age 9, when they had finished their arithmetic homework, I would let them use one of my calculators to check their work. It was a reward for doing the pencil and paper excercise. All three kids learned enough RPN to work my calculators, but only my son (now 22) actually prefers RPN. His two older sisters don't have much use for calculators these days.

I was in 9th grade (age 14) when the HP-35 came out. My dad bought one immediately. At the same time, my geometry teacher had a simple 4-banger with an equals sign. I learned both at the same time and almost instantly found that RPN was more logical and easier to understand, as well as more flexible and forgiving.



Rather than a calculator, I'd play number games with him. At dinner, we'd play "High/Low" where one person thinks of a number and the others take turns guessing. After each guess, the person with the number would say whether their number is higher or lower than the guess. Pretty quickly the kids figure out how to divide the unknown space in two. Even if they divide it roughly, if gives them a good sense of numbers.

Also around the same age, I taught my daughter how to calculate a 20% tip (move the decimal place and then double the result). Any time we're out, she grabs the check and computes a tip to the penny.

Basically, at this stage, you just want to them to have a sense of how numbers and math work.


About a year ago I was telling another engineer in our company about RPN when he asked. I told him algebraic tells you what you get, whereas RPN tells how you get there. He picked up and ran with that, got an HP calc, and told me a few days ago that now he could never go back to algebraic, that his mind just doesn't think that way anymore. He's adicted to RPN.


He knows what I mean... BTW, I'm an Electrical Engineer.

Luiz (Brazil)


In my sophmore year I took physics because I was queasy about cutting up animals even though they were pickled. In this class we learned slide rule but I always used pencil and paper because it was more natural for me.

I didn't even know calculators existed.

12 years after hifg school I was working for a civil engineer in Tucson when the HP 35 arrived in the hands of a part time employee U of A architect student. All the engineers and surveyors were going nuts over it.



I bought the 33S at auction and give it to children. I thought they could have fun with it, never mind solving problems. Kids adapt readily, they have no fear of computers or calculators. I thought the 33S was a good RPN calculator with scientific functions for keyboard use. Further advanced was the formula solver and finally RPN programming which is less complex than the RPL. Sam



I basically agree with Luis, however, how about my son's case?

My four years old sun likes numbers, especially the series number of a car, a motorcycle or a train, for instance 2000GT or GSX-R1000.

On one day while he's playing with a toy-like HP10s, pressing '1' '0' '0' '0' and saying

"One, Ten, Hundred, Thousand!, Oh, thousand + thousand makes two thousand!'

he began to learn about what digit is, and what does '+' means. Then asked me

"Does adding '0' (by pressing '0' key) mean multiply by 10? Does 'multiply by 10' means 10 bunch of something? right?"

A calculator with arithmetic display, like HP10S, seems to help him to begin learning about number and simple math visually.



I forgot the fractional math capability of the 33S for kids that are faced with pages of fraction problems. I see little use for fractions but I think kids still have to endure it. I admit i played with my original 35S for amusement and discovered solutions I would never have found with algebraic logic. The 33S switches to algebraic if "Johnny" has to keep in step with the class full of TI and Casio.


Fully agreed!

[rant]What a world we're in with parents pondering about a calculator for a 7-year-old?!? Teach'em to use their brains -- all of them! The time when they believe in everything a machine spits out will arrive earlier than you want it.[/rant]


Hi, Lyuka;

you see, based on your text, your sun was adding and multiplying by simply reasoning with zeroes (powers of ten, as we know already and he will know soon, as I see...). No mention to the '=' key so far... That is actually an abstract construction of reasoning for measurement and magnitude. I sincerely think that instead of using the '=' sign we should use the expression 'is equal to' as many times as needed until the kids use it implicitly, or ask for something to replace the expression. Then we show them how to write 'is equal to' with a signal, like the signals for add, multiply, etc. But I'd actually avoid it till they are studying variables and expressions. I remember once my younger brother asking me 'Why did the teacher write X=2, if X is not equal to 2? X is a letter, 2 is a number, how can they be equal?' The abstraction was missed, i.e., in a math expression X is not understood as a letter, it is a reference to an unknown quantity. It is a whole new set of meanings and a different use of known symbols. Abstraction is the key.


Luiz (Brazil)

Edited: 27 Oct 2009, 8:31 a.m.


Are you crazy Garth!

Again one more guy in the bay looking for old HP calculators!
Now I know why prices increases ;-)


Hi, Frank;

prices do not increase because of users, prices increase because of speculators... The MoHPC Classified Adds is a proof of that.


Luiz (Brazil)

Edited: 27 Oct 2009, 6:36 p.m.


This debate will never end. Try as I might, I just cannot "get" why some like RPN so much. So I gave up trying. To each his own.


Martin, I like RPN calculators because of their programmability. Keystroke programming is, in many ways, similar to assembler programming of the olden days. It is simple, has few rules and commands, executes pretty quickly on some of the current RPN calcs, and I enjoy the challenge of implementing an algorithm on a machine with a limited resource base, like the 12c. It's just fun!

Why some people like RPL amazes me. I like programming languages with 20 commands, not 2000.


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