convert to scientific notation

[Brian Yennie]

Randall,

I don't know about a power function, but reducing numbers to powers of  
ten is basically what a logarithm is for (assuming it's a base 10  
logarithm of course).

log 10 = 1
log 100 = 2
log 1000 = 3

etc.

For an "uneven" number, you could just round down the result for your  
purposes:

log 2,098,000 = 6.32 => 6

Since logarithms and exponents are basically interchangeable, you  
could probably rework any logarithmic formula into exponents, but may  
end up with a more complicated formula.

HTH

> You are correct brian.  Sorry.  But i know when i was younger and  
> smarter i had an equasion that converted a number to scientific  
> notation without counting digits.  Used the power "^" function  
> somehow.
>
> -----Original Message-----
> From: "Brian Yennie" <briany at qldlearning.com>
> To: "How to use Revolution" <use-revolution at lists.runrev.com>
> Sent: 4/20/2009 5:31 PM
> Subject: Re: convert to scientific notation
>
> Randall,
>
> You want the nth root and you are doing it correctly, but have a false
> assumption (the 10th root of 100 is NOT 2). I showed how to derive
> 10^x = 100, which is more relevant to scientific notation. Scientific
> notation does not involve taking the 10th root of a number, which I
> why I figure you are confused.
>
> Example: 2,098,000 = 2.098 x 10 ^ 6
>
> No 10th roots involved, in fact you can just count digits.
>
>> Not confused by what i mean.  How do i get the nth root of a number?
>>
>> -----Original Message-----
>> From: "Brian Yennie" <briany at qldlearning.com>
>> To: "How to use Revolution" <use-revolution at lists.runrev.com>
>> Sent: 4/20/2009 5:03 PM
>> Subject: Re: convert to scientific notation
>>
>> Randall,
>>
>> I think you are confusing two different concepts.
>>
>> 10^2 = 100, not 2^10 = 100.
>>
>> What you want is something like this:
>>
>> Step 1) 10^x = 100
>> Step 2) log 10^x = log 100
>> Step 3) x log 10 = log 100
>> Step 4) x = log 100 / log 10
>>
>> In short, you need to use logarithms and you'll get a formula where x
>> = log y / log z.
>>
>> If you were trying to solve x^10 = 100, then you could do what you
>> suggest and just raise both side to the (1/10)th power. But that
>> number will not be 2 -- it's about 1.58.
>>
>>
>>> I can't remember how to use power function "^" to find the nth root
>>> of a number.  To find the 2ndth root of a number we can use the
>>> "sqrt()" function.  But to find the nth root????
>>>
>>> For instance, lets say I want to convert a number to scientific
>>> notation (the 10th root of that number)... I used to know how to use
>>> the power function to do this.  Anyone remember how to do it?
>>>
>>> I tried to get the 10th root (scientific notation) of 100  (which
>>> should = 2) by:     100^(1/10) ... but that isn't it.
>>>
>>> Any ideas?  I feel brain dead.
>>>
>>> Randall
>>
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---
Brian Yennie
QLD Learning
(310)-367-7364