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Answers to Readers' Questions on Physical Science:

Using Calculator

The following 11 comments and questions have been sent in. They are listed according to date.

List of first 10 items

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Algebra problem

Question

July 26, 2010

(1) a2xa3=?

Daniel - Nigeria

20129

Answer

This is an Algebra problem. a^2 x a^3 = a^5.

See: http://www.school-for-champions.com/algebra/exponents_multiplication.htm

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How do I use a calculator with fractions?

Question

October 20, 2009

The calculator is great, thank you. How do I use it to calculate fractions and mixed fractions so the answer comes out as fractions instead of decimals?

Lisa - USA

18535

Answer

I don't know of any calculator that works with fractions.

Typically, you have to change a fraction or mixed number to a decimal and then change it back to a fraction. That is so cumbersome that it is easier to work with fractions with a pencil and paper. Also, fractions and mixed numbers usually are small enough numbers that you can easily do that.

But changing a decimal like 0.125 to 125/1000 = 1/8 is not too easy to do.

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What does +/- mean?

Question

September 14, 2009

On ordinary simple mathematical calculators, what does +/- mean and do??

And also TT, if you don't mind. Does it mean Pi? (As I got 3.14 etc. when I tapped it once.)

Vic - Australia.

18313

Answer

The +/- key changes the sign of what is displayed. For example, if you show -3, the +/- key will change it to +3.

On some calculators TT is the same as pi.

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'

Question

October 13, 2008

Hello,

I was just looking over some web resources and I believe you've made a minor error in one of the problems. The instructions for using the memory function on the scientific calculator say: "You want to add 1 + 2 and then MULTIPLY that by the sum of 8 - 3."

The instructions that follow are provided to ADD instead of multiply. No response is necessary, but I thought you might want to correct the error. I believe that has been a source of confusion for a previous poster.

Thanks

- USA

16642

Answer

Thanks for letting me know. I corrected the error.

I really want to update that whole section about using the calculator. It can be confusing.

I appreciate your feedback.

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Confusion on using calculator

Question

April 27, 2008

On this page: http://www.school-for-champions.com/science/calculations/using_calculator.htm

you multiply 3 x 5 and get 8 because Step 6 is wrong.

Adding to memory exercise: You want to add 1 + 2 and then multiply that by the sum of 8 - 3.

1. Click AC to clear all.
2. Add 1 + 2 and click =.
3. Click MC to clear the memory, then click M+ to add the value to memory.
4. Click AC to clear previous addition.
5. Then enter 8 - 3 =.
6. Click + to add another number.
7. Click MR to recall what is in memory. Then click =.
You should get a total of 8

To see how to add more to memory, click M+ and then MR. The 8 should be added to the 3 already in memory, giving you 11 when you recall memory.

- USA

15815

Answer

I'm not sure I understand what you are saying. I don't have anything about 3 x 5 in that exercise. It is all addition and subtraction.

Step 5 says 8 - 3 = 5. Step 6 says click + to add another number to 5. Step 7 recalls 3 from memory and = completes the addition.

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Using calculator with sin, cos and tan

Question

July 14, 2007

how can i use a calculator on sin,cos and tan
can u please tell me everything about as well thank you,and please plase
wright clearly because sometimes i go searching for math formulas and i read it and i come up with nothing.
thank you

mohamed - USA

14072

Answer

With the simple calculator on our site, you can enter the number of degrees first and then click on the trigonometric function to get its value. For example, enter the angle 30 degrees. Then click sin to get the value of 0.5 for the sine of 30 degrees.

Likewise, for the tangent of 40 degrees, you enter 40 and click tan to get 0.839.

But note that with this calculator, you must do the trigonometric function first before multiplying. You must be careful with it. In better calculators, you can do multiplication in any order.

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Does not understand e notation in scientific calculator

Question

November 1, 2006

Using Windows XP scientific calculator I calculated that a population explosion averaging a mere 1.1 people per person, with a generation interval of 20 years over 500,000 years would give us:

2x1.1^(500000/20) = 2.2^(25000) = 3.6899506269153657586250959350449e+8560 people alive on the earth.

But I do not understand the notation and the program's "help" does not help.

Can you explain what e+8560 means?

Thanks

Allan - UK

12284

Answer

Many scientific calculators use either e or E to denote raising 10 to an exponential power. Thus e+2 = 10^2 = 100. 5e+2 = 5*10^2. Also, something like 7e-3 = 7*10^-3 = 7/1000.

Note that since you are starting with 1.1, your accuracy is only 1 decimal point. Thus, your final number should be rounded off to 1 decimal point. Your answer should be 3.7*10^8560.

But this is certainly more people than would ever be on Earth, because there is not enough space for that many people. Estimates that the maximum number of people the Earth can sustain is about 12*10^9 people.

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Thanks for the basic "how to" for the scientific calculator

Question

May 23, 2006

Thanks for the basic "how to" for the scientific calculator. I appreciate the help since I had never used one before.

Kay - USA

11163

Answer

I'm glad that the material was helpful.

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Real estate formula

Question

January 4, 2006

Hello - when using the following real estate formula:
1-(1+(.07/12))-360
the -360 is smaller than the rest of the numbers
what does this mean and how do i calculate that on my scientific calculator?

Jackie - USA

9549

Answer

Something is wrong with the formula you gave. It seems like you are missing some multiplication or division. You have 1 - 1.00583 - 360 = -360.00583. That isn't right.

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Wants a scientific calculator

Question

December 28, 2005

this as been really helpfull, i am currently studying optical dispensing and there is a lot of maths which is all based in scientific calculations but except i need to buy one scintific calcultor with exp and inv buttons in it can you reccomend how through internet. lara from australia

lara - Australia

9485

Answer

Windows has a calculator that you can use until you purchase a real one. If you open the calculator and click View > Scientific, it will display one with most features.

Most office supply or computer stores sell scientific calculators. I would do that because you can see what it looks like and even try it out. Also, if it is not what you want, you can return in. Sometimes it is difficult to return calculators bought online. Amazon.com sells calculators, if you still want to buy online.

I hope this helps.

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