Why does a scientific calculator sometimes have a different answer than a regular calculator?

Answer 1

They actually don't. It is sometimes just the way they display the results. If you have formulas that end up creating results with decimal points, the spreadsheet might round them up. So something like 23.729999 that you might see on a calculator will show as 23.73 in a spreadsheet when it has been set to only show 2 decimal places. It still actually retains the true value, but displays it differently.

Another reason may be the way that you are doing some calculations. Without seeing what you are doing, it is hard to know. Spreadsheets calculate longer formulas than calculators do and calculators do them in a step by step process, sometimes in a different way. If you wanted to do 10+2*5 on a spreadsheet and a calculator you may get different answers, depending on how you do it. First, looking at it you are probably thinking the answer is 60. You would enter it into a spreadsheet like this:

=10+2*5

The answer you will get is 20, not 60. Using the laws of mathematics, the multiplication is done before the addition, so 2 multiplied by 5 is 10, plus 10 is 20. 20 is the correct answer. If you put 10 + 2 into a calculator and pressed the equals sign, you would get 12. If you then pressed * and 5 and the equals sign, it will give you 60. That is because you've broken the calculation into two steps. Depending on the way your calculator is set up, if you only do the last equals, you may get 20 too. To get the spreadsheet to give you 60, you type the formula like this:

=(10+2)*5

Some calculator have keys with ( and ) on them, which can be used for the same effect. So there are some reasons why you get a different result on a spreadsheet than you do on a calculator. It can be the way it is displaying the result or the way you do the calculation.

ACCOUNTING MODE

Another reason Excel may give you a different answer than your calculator is if you are doing accounting -- and you have your calculator in a common accounting mode where all answers are rounded off and displayed with 2 decimal places. In this mode, your calculator will actually round off each intermediate calculation. From an accounting perspective, this gives you intermediate results that can be shown in dollars and cents -- and the final result correctly matches these intermediate numbers.

This difference doesn't cause a problem if you are adding and subtracting dollars and cents -- or multiplying with whole numbers. However, if you multiply decimals or divide, then you can end up with a different result, often by a few cents.

For example, if you are calculating a daily interest accrual and multiplying by the number of days, you would have a calculation like this:

$50,128.45 x 5.15% / 365 days x 30 days = ??

Your calculator will multiply the first 2 numbers and round off the answer to 2581.62. Then, you type in 365, hit "/" and get the next result rounded off again to be $7.07 of daily interest. Multiply this by 30 and get $212.10.

Excel would calculate this to be $212.19 because it did not round off the intermediate results.

If you change your calculator to the floating decimal mode instead of the 2 decimal places (e.g. slide the switch from "2" to "F"), then you should get the same answer as Excel.

To get the calculator's accounting mode answer in Excel you would have to write the formula to round off each intermediate calculation, like this:

=round(round(50128.45*0.015,2)/365,2)*30

Answer 2

Five an example and i should be able to assist you.