# [plt-scheme] Help: Uber newb

 From: Todd O'Bryan (toddobryan at gmail.com) Date: Tue Jan 8 23:13:38 EST 2008 Previous message: [plt-scheme] Help: Uber newb Next message: [plt-scheme] Help: Uber newb Messages sorted by: [date] [thread] [subject] [author]

```Oh...it's not largest to smallest. You're supposed to create a 3-digit
number in the reverse order. (convert3 5 4 2) should give you the number
245. Most significant means that the 2 is worth 2 hundreds, whereas the 5 is
only worth 5 ones.

And I actually think the algebra hint is a bit of a red herring, although it
does give you a clue that the solution is arithmetic.

Todd

On Jan 8, 2008 11:09 PM, William Stanley <cpt_silverfox at hotmail.com> wrote:

>  Sorry, I should have clarified this exercise is 2.2.4 from www.htdp.org
>
> I have had no trouble with previous or later exercises and as I am trying
> to muddle my way through the text on my lonesome I have no way to easily
> check my work other then the "yup that works" method... and saddly I have no
> knowledge of an algebra function that does what this exercise asks... take 3
> numbers and spit it out in order of largest to smallest ie 1 2 3 = 321
> (hell the only reason I know algebra is the place to look is cause of that
> darned hint: "Use an algebra book to find out how such a conversion works."
>
> Thanks for the quick replies btw...
>
> Travis Stanley
>
> > From: clements at brinckerhoff.org
> > Subject: Re: [plt-scheme] Help: Uber newb
> > Date: Tue, 8 Jan 2008 19:23:36 -0800
> > To: cpt_silverfox at hotmail.com
> > CC: plt-scheme at list.cs.brown.edu
>
> >
> >
> > On Jan 8, 2008, at 7:08 PM, William Stanley wrote:
> >
> > > Exercise 2.2.4. Define the program convert3. It consumes three
> > > digits, starting with the least significant digit, followed by the
> > > next most significant one, and so on. The program produces the
> > > corresponding number. For example, the expected value of
> > > (convert3 1 2 3)
> > > is 321. Use an algebra book to find out how such a conversion works.
> > >
> > >
> > > Okay I had gone past this exercise but as I couldn't figure it out
> > > it was bugging me... and I must say its been a while since I
> > > regularly used algebra but after racking my brain for a while and
> > > googling for even longer I throw myself at your mercy... I am sure
> > > it is rather simple but I am stumped... sometimes I wish I could
> > > peek at those answers... even just to see if I got it right.
> > >
> > >
> > > Travis Stanley
> >
> >
> > I hate to be the design-recipe-bot, but... have you tried following
> > the design recipe? What are the examples you came up with? Are
> > there simple examples that you know how to do?
> >
> > John Clements
> >
>
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