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One thing I don't like about Google Calculator

Avrohom Eliezer Friedman (AEF) [PersonRank 10]

Wednesday, January 30, 2008
16 years ago4,603 views

Let me start out by saying that I love Google calculator. I use it for all my calculations. It's on the desktop and if I'm calculating a lot of numbers – I can see where I made a mistake and easily fix it and recalculate it instantly.

But there is one thing that I cam across today that didn't tickle my fancy. I wanted to know the 5 to the 30th power is. So I punched in 5 to the 30th and it gave me 9.31322575 × 10 to the 20th,GGLL:2007-50,GGLL:en&q=5+to+the+30th+power .

Although that is the correct answer, that didn't completely solve my problem as I really wanted a real number. So I punched in 9.31322575 × 10 to the 20th and it gave me 9.31322575 × (10 to the 20th) = 9.31322575 × 10 to the 20th .

Again technically correct – but that doesn't help me at all. So I just put in 10 to the 20th and it gave me 10 to the 20th = 1.0 × 10 to the 20th . Completely not helping me.

All I wanted it to tell me was that is 5 to the 30th = 186,264,514,923,095,703,125 (if that is the correct answer – I was trying to verify it) or eventually get to that sum.

Zim [PersonRank 10]

16 years ago #

The matter is how you tried to achieve the answer.
I did it this way:

If you query "powers of 5" and hit the I'm feeling lucky button, you'll have the answer.

Google has the answer to everything, but you need to do the right question before -or you may get a 42 instead- ;)

Rohit Srivastwa [PersonRank 10]

16 years ago #

But ZIM, thats not what Avrohom is trying to point out here

Yes, he might have tried this way to get his result.
But the result shown by Google Calculator is not what he or anyone else expected.

Tony Ruscoe [PersonRank 10]

16 years ago #

AEF: You're right, you should be able to choose which notation you want to use. However, to save yourself time in future, enter something like this:

[(5 ^ 30) / 186264514923095703125]

(Note: need for "to the 30th power")

That tells you the answer is 5, so you could work out that actually 5 ^ 29 = 186,264,514,923,095,703,125.

Ionut Alex. Chitu [PersonRank 10]

16 years ago #

5^30 = 931322574615478515625
as the built-in calculator from Ubuntu tells me (probably Windows Calculator will show the same thing in the advanced view)

So Google only tells you the first 9 digits which is more than enough for a basic calculator. I don't know if there's a good online calculator with advanced precision, but this one is a little better than Google:

Ionut Alex. Chitu [PersonRank 10]

16 years ago #

I've just realized you can use Google Spreadsheets for better math results. Just enter =5^30 in a cell.

Arthur [PersonRank 0]

16 years ago #

[put at-character here]Tony

[(5 ^ 30) / 186264514923095703125] gives 5 ..

[(5 ^ 30) / 186264514923095703130] also gives 5 ..

Tony Ruscoe [PersonRank 10]

16 years ago #

... presumably due to rounding though.

(And I'm sure you know this, but you only did minus 5 rather than divide by 5 on that large number, so it wouldn't change the outcome by a great deal.)

/pd [PersonRank 10]

16 years ago #

yeah calc should have a method to specify notation.

Ionut, wrt to Ubuntu O/s I remember about an FMEA program running of the Ubuntu plaftorm and the results seemed ok. However, when the same program was ported into the sun sparc env, there were minor variations in the results.

This boils down to the actually Gates available within a CPU itself. Precision calc's are Dependant on hardware too..!!

Avrohom Eliezer Friedman (AEF) [PersonRank 10]

16 years ago #

Wow – you guys are great.

Se what happened is – a friend of mine posted as his status that said "5 to the 30th = 186,264,514,923,095,703,125" So i wanted to verify if he was correct – so I turned to my everyday calculator – the Google Calculator. After that was no help I used a slight variation of Zim's method. (This was before I posted it.) I found myself on this page which showed that he was wrong. So I told him that he was wrong. Then he said he just did it by calculator and he was correct and whoever posted – posted incorrectly. Had Google Calculator showed me he was wrong I couldv'e proved it. I didn't think of Tony's method which would've solved the problem. However, you have to know a bit of math for that one. :).

Anyways – thanks for helping me out here!

George R [PersonRank 10]

16 years ago #

You can check this in your head by inspection.
The last three digits should be "625" not "125".
Even powers of 5 (i.e. powers of 25) greater than 25 should have "625" as the last three digits.
Odd powers of 5 greater than 25 should have "125" as the last three digits.

5^3 = 125
5^4 = 625

125 * 5 = 625 mod 1000
625 * 5 = 125 mod 1000

5^30 = 5^4 * 5^26 = 625 mod 1000

5^googol = 625 mod 1000

Below are results from a calculator on my computer.
5^29 = 186264514923095703125
5^30 = 931322574615478515625

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