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View Full Version : MATH / move decimal place left while retaining original value ?



Ken
07-22-2015, 04:58 PM
Take the number 2.4863 for example. Or 12.4863. Is there a way to express or state the same value so that there are no numbers to the left of the decimal point? Or at least so the value is approximately retained? Maybe with a string of leading 9's or something of the sort? (.999999924863)

Thnx in advance !

Oops. One more question. How about the reverse. Can you shift the decimal point right while retaining the original value so there are no numbers to the right of the decimal point? Most likely not I suppose.

Myrealana
07-22-2015, 05:14 PM
Scientific notation.

12.4863 = 124863 *10^(-4)

It's not proper, but it works.

You can also change your units. If you're talking kilometers, for example you can speak in meters or centimeters and lose the decimal.

tlustoprd
07-22-2015, 05:18 PM
I'm not sure if this is what you want, but have you considered scientific notation? 2.4863 written as 0.24863x10^1 (with no numbers on the left save for 0) or 24863x10^(-4). Written exactly as the "input interpretation" row here: http://www.wolframalpha.com/input/?i=24863x10^%28-4%29

Basically, what you do is to multiply/divide the number by ten to the power of X, the X acting as a shift, moving the number either to the left or right.

Another way of writing the number could be using different bases, but it might be difficult to find the right base where this would work for a specific number. For what purpose do you want this?

Edit: oops, Myrealana was faster.

Ken
07-22-2015, 05:26 PM
Thnx! Converting may work well. From inches to centimeters, perhaps.
The base of the number is in inches, if my guess at what a base is.
Scientific notation probably wouldn't suit, but it's good to know how that is formulated. I always wondered about that.
And now I am wondering if there is a slightly smaller measurement than centimeters, in case centimeters doesn't do the trick? The more obscure the better. Maybe checking measurement systems of different countries might supply an answer...

tlustoprd
07-22-2015, 05:40 PM
Inches and centimetres? Never mind the base (that's something like... how many unique digits are used... binary base - 0 and 1; decimal base 0,1,2,3,4,5,6,7,8,9), it's not a good idea in this case.

The SI metric system of measurements has these unit prefixes: https://en.wikipedia.org/wiki/Unit_of_length
Millimeters are "slightly" smaller than centimeters. 10 millimeters = 1 centimeter.

Ken
07-22-2015, 05:51 PM
I gotcha. 0-9. So ten unique digits in all. Converted to the same, I suppose. Thanks. I may try a measurement system that's specific to a country. An obscure one if it is a base ten too. If not it would probably be a hassle and more trouble than it would be worth. I wonder if China has a different system of measurement? Or Australia? Brazil? Japan? Uruguay? Etc.

Thanks for the info and link!

King Neptune
07-22-2015, 06:41 PM
I gotcha. 0-9. So ten unique digits in all. Converted to the same, I suppose. Thanks. I may try a measurement system that's specific to a country. An obscure one if it is a base ten too. If not it would probably be a hassle and more trouble than it would be worth. I wonder if China has a different system of measurement? Or Australia? Brazil? Japan? Uruguay? Etc.

Thanks for the info and link!

Nearly the whole world has been co-opted into the Metric System. There are odd earlier systems of measures that might do what you want. Barleycorns are sometimes a useful measure; they are mostly used for shoe sizes.

Ken
07-23-2015, 02:38 AM
Barleycorns are sometimes a useful measure; they are mostly used for shoe sizes.

Seems delightful. May be just the thing.
Definitely will research. Thnx !

Robert Dawson
07-23-2015, 02:55 AM
Take the number 2.4863 for example. Or 12.4863. Is there a way to express or state the same value so that there are no numbers to the left of the decimal point?

.24863x 10^1, .124863x10^2 - denormalized scientific notation. It's a little nonstandard, but unambiguous. My only question - why?

"Engineering notation" sets some sort of precedent for this: the mantissa is partly denormalized, anywhere between 1 and 1000, and the exponent is always divisible by 3, paralleling SI notation. So instead of 12345.6 meters or 1.2345 x 10^4 meters, you write 12.3456 x 10^3 meters which is clearly 12.3456 kilometers.

How about the reverse. Can you shift the decimal point right while retaining the original value so there are no numbers to the right of the decimal point?

24863/10000, or 24683 x 10^-4. Again, not quite sure why you'd want to do this, and it is definitely not the usual way to represent this number.

Ken
07-23-2015, 03:10 AM
Thnx Robert. Really just for the format. Same as wanting to turn a fraction into a single number. (1/4 = .25) For me, it would be convenient to do away with the decimal which is awkward. I figured there might just possibly be a way. And there is, by converting the measurement into another system of measure which should work fine.

scrub puller
07-23-2015, 03:17 AM
Yair . . .

A bit off topic but . . .

In the real world "centimetre" is a redundant unit and (in Australia) is never used except by the press and casual users.

In most trades the millimeter and meter are used exclusively.

For instance a sheet of ply is twelve hundred by twenty four hundred (1200mmx2400mm) or a piece of 50mm steel pipe may four thousand eight hundred long (4800mm or 4.8 meters).

Introducing centimeters confuses a simple system.

Cheers.

Ken
07-23-2015, 03:26 AM
Interesting. Thnx.
So 2.4863 inches = 63.15202 millimeters. And just like that I've moved the decimal point one place to the right !

Ken
07-24-2015, 02:48 PM
Have settled on a Planck length = 1.616199(97)10−35 metres (https://en.wikipedia.org/wiki/Metre). (The smallest calculable measurement.)
Does anyone know what that would work out to in inches?

1 inch = X planck lengths?

also, what this scientific notation number is in plain digits 1.616199(97)10−35 ?

source: wikipedia

tlustoprd
07-24-2015, 03:06 PM
6.3629892 10(-34) inches

You could use Wolfram Alpha for these queries. http://www.wolframalpha.com/ (or sometimes google)
It's fast. You just have to supply a question. For example, http://www.wolframalpha.com/input/?i=planck+length+to+inches returns 6.3629892 10(-34) inches

As for scientific notation to a plain number... well, it would be a lot of zeroes followed by 161619997. The exponent (-35) says how many. In this case, 35 (including the zero left of the decimal point). 0.000...000161619997

Ken
07-24-2015, 04:09 PM
Thnx tlustoprd. I appreciate it !