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Mac help & tips
helliott1
Member

Posted: Fri, 27 Apr 2007 07:56PM

Hi everybody !
Got a bit of a dilemma…
The boy has been doing factors in maths recently, and he also chose to do the extra question, which was: find all 96 factors of 210210!!!
He used NeoOffice Calc (i.e. the spreadsheet component) to make a spreadsheet listing all the divisions into 210210 up to the finishing point (458), and then copied down all the whole numbers (they're not factors if they go into decimals). He asked me if there was a way to mark all the factors, rather than him having to look through all of them !
I did a Find and Replace: I told it to replace any decimal points with the word NOT. It worked, but is there a way to flag the ones WITHOUT decimal points?

Posts: | Location: UK | IP: Logged
Member

Posted: Fri, 27 Apr 2007 11:29PM

helliott1,

MOD( dividend; divisor );

This is the modulus operator, it calculates the remainder of a division.

If the modulus is zero, then there was no remainder, it was a whole number.

ie,

QUOTIENT( 6;4 ) = 1
MOD( 6;4 ) = 2

6=(1*4)+2;

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helliott1
Member

Posted: Sat, 28 Apr 2007 02:32PM

Thanks for that, but is there a way to put a word in, say, the next column to clearly mark out the factors?

Posts: | Location: UK | IP: Logged
Member

Posted: Sat, 28 Apr 2007 03:44PM

helliott1,

If you can make a spreadsheet with the row number in column A
and =MOD(210210;A1) in column b.

Select All,

Then do Data->Filter->Standard Filter...
and use ColumnB = 0

It will only list the factors.

Jobs a good 'un

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Clive603
Member

Posted: Sat, 28 Apr 2007 08:50PM

helliott1,

Erm, doesn't using a computer rather defeat the object of the exercise which is surely to help get a general feel for integer numbers and their relationships.
210210 is obviously an interesting number to factorise from this point of view.
Its many years since I had to deal with this sort of stuff from the schoolroom point of view but I presume he has been taught the simple, albeit mildly tedious, methods for doing this sort of thing by hand. I realise things have changed but in my schooldays a problem like that would have been less than half a normal weekday homework assignment (1 hour each for 3 subjects) and certainly unworthy of a weekend blockbuster (2 1/2 hours each for 5 subjects).
Nearest I get to it these days is to maintain a basic competence in the method of continuous fractions should I need to set-up an obscure screw-cutting gear train or figure out a which circle to use on a dividing head when the little man who lives under the desk has hidden the settings tables. (That reminds me, must get round to making the other 4 plates in the wide range set for my Cincinnati dividing head)

Posts: | Location: Crowborough, UK | IP: Logged
helliott1
Member

Posted: Sun, 29 Apr 2007 01:06PM

Clive603,
because 210210 has so many factors, apparently the maths teacher said we could use a calculator or spreadsheet to help.
You think I'd let him cheat?

Posts: | Location: UK | IP: Logged

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