Questions regarding calculators such as the TI-83 (Plus), HP 50g, and other calculator models.

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29
votes
4answers
12k views

Calculator algorithms

Does there exist a good reference on the algorithms used by calculators, especially on the trigonometric and transcendental functions? I would still like to know how Casio generates its random ...
25
votes
6answers
2k views

Why does my calculator show $2^{-329} = 0?$

On my calculator, I usually get a $0$ when I divide something by $2$, a lot of times if that makes sense, but I was just wondering why does $2^{-329} = 0?$
21
votes
7answers
2k views

“Why do I always get 1 when I keep hitting the square root button on my calculator?”

I asked myself this question when I was a young boy playing around with the calculator. Today, I think I know the answer, but I'm not sure whether I'd be able to explain it to a child or layman ...
16
votes
3answers
894 views

Why would a calculator have base 5?

I have a calculator that I found recently that has a base 5 option. It has options labelled HEX, BIN, DEC, OCT, and PEN. My son set it on PEN, and no numbers above 4 worked anymore. Playing around ...
14
votes
7answers
2k views

Conflicting limit answers using calculator and wolfram alpha

I want to evaluate $\lim\limits_{x\to0} \dfrac{\tan(x) - \sin(x)}{(\sin(x))^3}$, Calculator says it's 0 when substituted with 0.0000000001. Wolfram Alpha says it's 1/2. The Problem Set says the ...
13
votes
9answers
13k views

How to calculate $e^x$ with a standard calculator

Is there a simple method for calculating the $e^x$ ($x\in\mathbb{R}$) with a basic add/subtract/multiply/divide calculator that converges in reasonable time, preferably without having to memorize ...
10
votes
4answers
3k views

How do pocket calculators calculate exponents?

I'd like to know specifically how a pocket calculator (TI calculators also apply) calculates $e^{0.1}$, and what methods or algorithms pocket calculators use in order to produce their answer.
10
votes
2answers
8k views

What exactly do the sin, cos, tan buttons do on a calculator?

I understand they mean sine, cosine, tangent, but what exactly is the calculator doing when I enter an angle and press those buttons? Edit: To help others better understand my question, my question ...
9
votes
2answers
262 views

How do I find, algorithmically, which parts of a given function are interesting to graph?

I'm building a program that does 2D graphing, and was wondering: How can I determine the default zoom level and x/y extents to display on screen, in such a way as to maximise the 'interesting' parts ...
6
votes
7answers
1k views

How calculators do trigonometry [duplicate]

I need to use a calculator to find trigonometric ratios like $\sin(41),\cos(32)$. How do calculators work for trigonometry? Also, as calculators are invented by the human mind can we do it mentally? ...
6
votes
3answers
2k views

What is the definition of $2.5!$? (2.5 factorial)

I was messing around with my TI-84 Plus Silver Edition calculator and discovered that it will actually give me values when taking the factorial of any number $n/2$ where $n$ is any integer greater ...
6
votes
3answers
411 views

Express “if true, then 1 else 0” in a formula suitable for Desmos calculator

In programming, often the value of True is also 1, and False is 0. This means that: (x>5)*4 will return 4 if x is greater than 5 (because ...
6
votes
3answers
1k views

Base-2 exponentiation bug on Citizen SR-270X for $2^{255}$?

According to my calculator, $2^{255} = 0.5$. Also, for the range $2^x, x\in[254.5, 255.5)$ the result spans $[0.3535533906, 0.7071067812]$. Outside of that, the answers seem correct. Curiosly, $2^{...
5
votes
3answers
590 views

Is there a way to use a calculator for logarithmic form equations that aren't base 10 or base e?

Is there a way to use a calculator for logarithmic form equations that aren't base 10 or base e? I just find this really hard to believe and quite unacceptable that the only way to do this is ...
5
votes
4answers
148 views

Rational Exponents on Calculator

I'm confused as to why my calculator is saying that $$x^\frac{n}{n}=x$$ when $n$ is an even integer. I was under the impression that $$x^\frac{n}{n}=\sqrt[n]x^n=|x|$$ when $n$ is an even integer. ...
5
votes
2answers
131 views

Why are there conflicting results for integration?

Using my calculator, I had tried to evaluate the definite integral $$\int_{0}^{1}x^x \mathbf{d}x$$ However, according to my CASIO $fx-570$ES, the result was Math ERROR, which led me to believe that ...
4
votes
4answers
547 views

A question about calculators (are $\sin^2 49^{\circ}$ and $\cos^2 49^{\circ}$ irrational?)

Are $(\sin 49^{\circ})^2$ and $(\cos 49^{\circ})^2$ irrational numbers? When you enter, $(\sin 49^{\circ})^2$ in a calculator, it shows a long number (and if it is irrational, then clearly the ...
4
votes
3answers
486 views

Wrong calculation by a calculator

Today I was working on some chemistry problems . Many of you might know it involves some big exponents. So today I just entered in one of my calculators (which might not be strong) as it was inbuilt ...
4
votes
5answers
645 views

Calculate ln(x) using 8-digit calculator

I have a bit of a unique problem. Well, maybe not a problem because I'm really just curious about it, but... I have a simple 8 digit calculator. It has +, -, x, /, and a constant operation function. ...
4
votes
4answers
5k views

Calculator similar to Desmos but for 3D

Is there a calculator with functionality similar to Desmos but in 3 dimensions? I am looking to learn about families of quadric surfaces so I am looking for a 3D calculator with sliders.
4
votes
1answer
88 views

A nice way to do Euler's method on a calculator?

As part of the calculator paper for IB (International Baccalaureate), we may be asked to do Euler's method, for say, 10 iterations. While it is feasible to do with a calculator (slightly easier if ...
4
votes
1answer
140 views

Calculating a sum which includes binomial coeffeicients

Some formula for calculating the probablity that the difference between the number $6$ and the average of accidentally selected $100$ points among $10000$ points which are distributed in the interval $...
3
votes
6answers
813 views

Why do I disagree with my calculator?

I followed the order of opperations but my answer disagrees with my calulator's. Problem: $331.91 - 1.03 - 19.90 + 150.00$ Calculator answer: $460.98$ My answer: $162.98$ Why the ...
3
votes
3answers
7k views

How do you plot $x = y^2 - 6$ on a graphing calculator?

I have a graphing calculator app (Graphing Calculator+) that only allows me to enter $x$ as a variable, but I need to graph $x = y^2 - 6$. I haven't used a graphing calculator in awhile. Is this ...
3
votes
4answers
17k views

TI-83 Plus: Is it possible to find the eigenvalues on this calculator?

I searched the Internet and can't seem to find a source on how to find the eigenvalues on a TI-83 Plus calculator. Can anyone give me a hand?
3
votes
3answers
57 views

Difference between $(-x)^{1/n}$ and $-x^{1/n}$?

I know these seems to be splitting hairs, but according to two different calculators, there's a real difference. For e.g, $(-8)^{1/3}$ computes to NaN, where $-8^{1/3}$ computes to $-2$. Though am ...
3
votes
5answers
5k views

What type of input does trigonometric functions take in

I see in my Book that 45 deg is equivalent of π/4 . Ι also do the conversion if I simply convert degrees into radians like this 45* π/180 = π/4 radians and ...
3
votes
3answers
6k views

is there a CIS button on graphic calculators (Casio/TI)

Is there a cis (CosX + iSinX) Button in CASIO graphic calculators ? if so where its ? if no is there any turn around for it ? PS. I got a CASIO fx-9860G Thanks
3
votes
2answers
96 views

Calculator question involving $\log_2$?

I have a question, I have a calculator that does $\log$ but I think it does it it in a base ten format for example $\log_{10}(100)=2$ I am wondering how I can solve $\log$ using a base of 2 for ...
3
votes
1answer
84 views

Why Can my Phone Calculator do $e^{\pi\sqrt{-1}}$ but not $\sqrt{-1}$?

When I type in the identity $e^{\pi\sqrt{-1}}$ on my phone calculator (LG phone running Android), I get the correct result of $-1$ However, when I simply type $\sqrt{-1}$, it returns an error. Why ...
3
votes
2answers
145 views

How to find high power numbers modulo

How can I find high power number modulo number. What If I have to do it with the calculator or if the calculator is not allowed in exam. For example: $174^{55} \pmod {221} \equiv 47$
3
votes
4answers
3k views

Weird stuff happening with complex numbers on a ti-84

So, I'm trying to do some calculations for my Electrical engineering homework. This requires a bit of algebra with complex numbers. I have been finding that some of the calculations that my calculator ...
3
votes
1answer
110 views

Getting the Total value from the Nett

I can't figure out this formula; I need some help to write it out for a php script. I have a value of $\$80$. $\$80$ is the profit from a total sale of $\$100$; $ 20\%$ is the percentage ...
3
votes
1answer
108 views

How to get 2 using a standard scientific calculator without pressing the number buttons 0 to 9 and the buttons $+-\times\div$?

I was challenged by a friend to get a number 2 by using a standard scientific calculator but without pressing the number buttons 0 to 9 and the buttons $+-\times\div$. I could get 1 from $\ln e=1$. ...
3
votes
2answers
2k views

Simplfy a complex matrix into a real one

I encounter systems of linear complex equations (At most 3 equations) in my circuit analysis course. The calculator I am using is Casio fx-991ES and it only accepts real elements when in matrix or ...
3
votes
0answers
239 views

Math for Future Value of Growing Annuity

Am I working this out correctly? I need to verify that my code is correct... $$1000 \cdot \left(\frac{(1 + 0.1 / 12)^{40 * 12} - (1 + 0.06 / 12)^{40 * 12}}{(0.1 / 12) - (0.06 / 12)}\right)$$ ...
3
votes
1answer
76 views

Texas TI-alternatives

I've been using a Texas TI graphing calculator at school and am wondering if there are programs for the PC that function similarly (with similar features) as those calculators. I don't need an ...
3
votes
0answers
252 views

How does my $10\times10$ abacus work?

How does this $10\times10$ abacus work? More specific: Counting: is it common to count from 1 to 100, or from 1 to 9.999.999? How does addition work? How does multiplication work? Are there any ...
2
votes
6answers
24k views

Calculate remainder on Casio fx-991 ES Calculator

Is it possible or not to calculate remainder through use of Casio fx-991 ES Calculator. If possible then how for example :- I have to calculate remainder of ...
2
votes
1answer
299 views

Negative × Negative = Positive… right?

The wife and I were doing homework together, and we noticed something really strange when charting quadratics with a TI-series graphing calculator: ...
2
votes
1answer
6k views

Calculating the percentage of the difference between two values

If I have the following two different values for x: x = 0.022 x = 0.020 And, if I want to calculate the percentage of the difference (change) in x, will it be? ---> 0.022 - 0.020 = 0.002 ---> 0....
2
votes
1answer
76 views

TI-84 gives 100 for $\frac{d}{dx}\sqrt[3]{x}\,\big|_{x=0}$

My TI-84 Silver Edition is doing something strange. If $f(x)=\sqrt[3]{x}$, $\frac{d}{dx}\sqrt[3]{x}=\frac{1}{3\sqrt[3]{{x^2}}}$ At $x=0$, $\frac{d}{dx}f(0)$ is undefined. When I type $\frac{d}{dx}\...
2
votes
2answers
277 views

In my calculator why does $\sqrt4 -2=-8.1648465955514287168521180122928e-39?$

I have tried this on my Windows 7 calculator with $\sqrt9 -3 $ it too gives some weird answer- ie$1.1546388020691628168216106791278e-37$. And so for any $n$(positive) $\sqrt n^2-n= wierd_ .answer$ Why ...
2
votes
1answer
71 views

Why does this always equal $1$?

One of my friends told me this. Take a calculator and continuously input $\cos\tan\sin\cos\tan\sin\ldots$ any number of times you want and finally in the place of the angle measure place any value of ...
2
votes
2answers
4k views

How to find antilog with simple calculator?

I know how to find log to base $10$ using simple calculator: say if you want to find log of $12$ you can do as blow: Step 1: $13$ times $\sqrt{\star} \implies 1.00030338$; Step 2: subtract 1: $1....
2
votes
1answer
338 views

How can I see alternative trigonometry solutions on a calculator?

When doing inverse trigonometric equations on a calculator, only the lowest positive solution is shown. How can I see alternative solutions (specifically for a Casio FX85ES)? Current behaviour: $$sin^...
2
votes
1answer
43 views

What does my TI-83 or other TI graphing calculators use to numerically approach certain integrals?

I assume that most graphics calculators try to solve things analytically (where possible within reasonable computing time and power). Otherwise do they use numerical approximations for definite ...
2
votes
1answer
247 views

What is the answer of this problem solving question?

You need to order 4 plastic cups for each of the 800 runners. Plastic cups are sold in 2 different pack sizes and you must choose one type of pack only. A pack of 500 costs £12.50 or a pack of 800 ...
2
votes
3answers
2k views

How to determine end behavior with my TI-83

So, I need to determine the end behavior of $P$ for this equation: $$P(x) = −x^5 + 3x^2 + x.$$ If possible, how is this done?
2
votes
0answers
60 views

Pocket Calculators- Obsolete? [closed]

I hope this fits into "software that mathematicians use" within the acceptable topics for this site. Are there still any instances where pocket calculators prove useful to professional mathematicians ...