Problem 032

A place to air possible concerns or difficulties in understanding ProjectEuler problems. This forum is not meant to publish solutions. This forum is NOT meant to discuss solution methods or giving hints how a problem can be solved.
Forum rules
As your posts will be visible to the general public you
are requested to be thoughtful in not posting anything
that might explicitly give away how to solve a particular problem.

This forum is NOT meant to discuss solution methods for a problem.

In particular don't post any code fragments or results.

Don't start begging others to give partial answers to problems

Don't ask for hints how to solve a problem

Don't start a new topic for a problem if there already exists one


See also the topics:
Don't post any spoilers
Comments, questions and clarifications about PE problems.
friol
Posts: 4
Joined: Mon Apr 14, 2008 8:06 pm

Problem 032

Post by friol »

Hello.
I think I've found the solution to problem 32, but projecteuler.net rejects it.

Problem 32 asks:
"Find the sum of all products whose multiplicand/multiplier/product identity can be written as a 1 through 9 pandigital. "

I think these are the products:

[edit]Removed correct solution set[/edit]

and the sum of the products is _____, but it does not seem to be the answer.
What I'm doing wrong?

Thanks

User avatar
euler
Administrator
Posts: 3317
Joined: Sun Mar 05, 2006 4:49 pm
Location: Cheshire, England
Contact:

Re: Problem 32

Post by euler »

I've edited your post to remove the list, as it is correct. Remember, the word product means the answer you get from multiplying. You might find the hint in the problem statement helpful. :wink:
Image
impudens simia et macrologus profundus fabulae

friol
Posts: 4
Joined: Mon Apr 14, 2008 8:06 pm

Re: Problem 32

Post by friol »

Now I've got it 8-D
Thanks.

User avatar
euler
Administrator
Posts: 3317
Joined: Sun Mar 05, 2006 4:49 pm
Location: Cheshire, England
Contact:

Re: Problem 32

Post by euler »

You're welcome, and congrats.
Image
impudens simia et macrologus profundus fabulae

vzhilyaev
Posts: 1
Joined: Fri Oct 17, 2008 2:50 pm

Re: Problem 32

Post by vzhilyaev »

Am I getting it right that multiplicand/multiplier/product should have in total exactly nine digits?

User avatar
daniel.is.fischer
Posts: 2400
Joined: Sun Sep 02, 2007 11:15 pm
Location: Bremen, Germany

Re: Problem 32

Post by daniel.is.fischer »

Yes.
Il faut respecter la montagne -- c'est pourquoi les gypaètes sont là.

User avatar
marco6
Posts: 3
Joined: Sat Nov 08, 2008 5:32 pm

Problem 32

Post by marco6 »

can anyone explain me what does "pandigital" mean?
thanks

User avatar
Georg
Posts: 157
Joined: Mon Jan 21, 2008 7:00 am
Location: Mannheim, Germany
Contact:

Re: Problem 32

Post by Georg »

Problem 41 (View Problem): We shall say that an n-digit number is pandigital if it makes use of all the digits 1 to n exactly once.

User avatar
euler
Administrator
Posts: 3317
Joined: Sun Mar 05, 2006 4:49 pm
Location: Cheshire, England
Contact:

Re: Problem 32

Post by euler »

Good question, marco6. I hadn't realised that a definition was missing from that question. I've added the same definition from problem 41 (thanks, Georg) as an introduction to the problem.

Problem 32 (View Problem)
Image
impudens simia et macrologus profundus fabulae

User avatar
marco6
Posts: 3
Joined: Sat Nov 08, 2008 5:32 pm

Re: Problem 32

Post by marco6 »

Thank you for your answer!

User avatar
Sunhill
Posts: 9
Joined: Tue Apr 29, 2008 10:36 am
Location: Sydney, Australia
Contact:

Re: Problem 032

Post by Sunhill »

Mods: A very small typo in the last word of the first paragraph - "pandigitial".

User avatar
daniel.is.fischer
Posts: 2400
Joined: Sun Sep 02, 2007 11:15 pm
Location: Bremen, Germany

Re: Problem 032

Post by daniel.is.fischer »

Thanks - fixed.
Il faut respecter la montagne -- c'est pourquoi les gypaètes sont là.

masteusz
Posts: 2
Joined: Fri Jan 21, 2011 12:37 pm

Re: Problem 032

Post by masteusz »

Hello,
I think that I have found correct solution but ProjectEuler rejects it so I have a question:
For example is 39 x 186 = 7254 and 186 x 39 = 7254 counted as one or two different pandigital identities?
Image

User avatar
jaap
Posts: 551
Joined: Tue Mar 25, 2008 3:57 pm
Contact:

Re: Problem 032

Post by jaap »

One. The problem clearly states:
HINT: Some products can be obtained in more than one way so be sure to only include it once in your sum.
Note that this is even stricter than just swapping the two factors.

masteusz
Posts: 2
Joined: Fri Jan 21, 2011 12:37 pm

Re: Problem 032

Post by masteusz »

Thanks, I omitted the word "once" while I was reading :)
Image

jhughes
Posts: 1
Joined: Sun Feb 07, 2010 4:37 am

Re: Problem 032

Post by jhughes »

Could someone explain to me what this problem is referring to by "identity"? I know it's meaning in other contexts, not this one.
Thanks in advance!

User avatar
rayfil
Administrator
Posts: 1405
Joined: Sun Mar 26, 2006 5:30 am
Location: Quebec, Canada
Contact:

Re: Problem 032

Post by rayfil »

When you have an equal sign (=), it means that both sides must be considered identical. Thus, 39 × 186 can be considered an identity of 7254. Similarly 78 x 93, 31 x 234 and 13 x 18 x 31 would also be considered identities of 7254 among many others.
When you assume something, you risk being wrong half the time.

Spura
Posts: 8
Joined: Mon May 16, 2011 4:49 pm

Re: Problem 032

Post by Spura »

Do we have to consider solutions with multiple multiplicands?
X * Y * Z = U

?

User avatar
hk
Administrator
Posts: 10883
Joined: Sun Mar 26, 2006 10:34 am
Location: Haren, Netherlands

Re: Problem 032

Post by hk »

Spura wrote:Do we have to consider solutions with multiple multiplicands?
X * Y * Z = U

?
No
Image

User avatar
Molx
Posts: 3
Joined: Tue Jun 07, 2011 6:44 pm
Location: Brazil
Contact:

Re: Problem 032

Post by Molx »

Spura wrote:Do we have to consider solutions with multiple multiplicands?
X * Y * Z = U

?
No, only Multiplicand * Multiplier = Product
Problem 32 (View Problem)
Image

Post Reply