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Google calculator - handy, but not always correct

By Murray Bourne, 27 Aug 2008

Have you ever played with Google's nifty calculator?

Just go to Google and type something like the following into the search field:

4 + 5

The answer will come back at the top of the search results.

What else can it do? Well, lots, actually.

Try these:

  • Raise to a power - Example: 5^2
  • Square root - Example: sqrt(34.7)
  • Trigonometric functions - Example: sin(3pi/4) [It assumes the angle is in radians]
  • Counting (in the study of probability) - Example: If you need to know the number of ways 5 objects can be chosen from 14 objects, put: 14 choose 5

There are more examples and information here: Calculator.

BTW, you may not need to actually go to the site. If you have Google selected as the search in Firefox, the answer will appear as a "suggestion" and you don't even need to leave your current page:

Google calculator in Firefox

Large Numbers and Calculators

Most hand-held calculators are limited when it comes to large numbers. This is a problem if you want to find the factorial of some large-ish number. For example, an old 8-digit calculator I have here can go up to 69! only (the answer is 1.71122 Γ— 1098). [This answer is almost equal to the number "googol" (10100), which was the number that inspired the companies name.]

Now, I can do up to 170! (The answer is 7.25741562 Γ— 10306). After that, it falls over. But hey, not bad.

Calculator Mistakes

Now, what about those mistakes I was talking about? The following article from writer Steven Shankland shows that when the numbers are huge, the calculator could be off a bit (or a lot).

See Google's calculator muffs some math problems

I tend to agree with Shankland. They should put effort into getting this right, with the amount of resources at their disposal you'd think they could...


UPDATE (Dec 2018): Google's phone calculator app appears to have solved most of the issues mentioned by Shankland's (old now) article.

See the 6 Comments below.

6 Comments on “Google calculator - handy, but not always correct”

  1. Li-sa says:

    I tried Google calculator one day yesterday.
    It is possible that the large numbers involved in Google's Math == FAIL was due to overflow errors. The calculator might only be able to read a certain number of significant figures.

  2. BILL says:

    GOOGLE CALCULATOR and also the App that is sold upon which the Google Calculator is based upon has a massive error. An error that can actually be a major threat to everyone, whether you use it or not. The error is in the calculation of Trig problems and vector analysis. Example the sin of 260 degrees is stated as: +0.68323970381. The correct value is -0.984807753.

    The Google calculator is completely wrong, not even close to being right.

    Since these sin, cosine and tangent calculations are all commonly used in vector LOAD analysis in Civil Engineering. It means that buildings, bridges, and everything we construct could have horrible life threatening mistakes if the engineers used any of these computer calcuators to make their designs.


  3. Murray says:

    @Bill: The result from a Google search bar for sin 260 degrees gives the correct result of -0.98480775301. I don't know which app you mean by "the App that is sold upon which the Google Calculator is based upon". Let me know and I'll check it out.

    Your all-caps final statement is over the top.

  4. goldierocks says:

    Google calculator can be hopelessly wrong. For energy calculations it can be out by a factor of 1000 times (e.g. calorie to kilojoules - they have confused calories and kilocalories)

  5. Murray says:

    @goldierocks: There are several different definitions for calorie, as this Brittanica article points out.

    Google's calculator is correctly reporting the (arguably more asked) conversion of the Calorie (upper case C), which most dieters are interested in.

    Yet another case where the small number of countries still using non-metric units should change to kJ.

  6. Teresa says:

    The calculator is giving you the answer In radians. Change it to degrees.
    Sin(260 radians) = .683239...
    Sin(260 degrees) = -.9848...

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