Challenge Questions Blog

Challenge Questions

Stop in and exercise your brain. Talk about this month's Challenge from Specs & Techs or similar puzzles.

So do you have a Challenge Question that could stump the community? Then submit the question with the "correct" answer and we'll post it. If it's really good, we may even roll it up to Specs & Techs. You'll be famous!

Answers to Challenge Questions appear by the last Tuesday of the month.
Previous in Blog: 10 Questions to Find a Number (August 2025 Challenge Question)   Next in Blog: Steam Train Showtime (Oct. 2025 Challenge Question)
Close

Comments Format:






Change Mode
Close

Subscribe to Discussion:

CR4 allows you to "subscribe" to a discussion
so that you can be notified of new comments to
the discussion via email.

Close

Rating Vote:







Add Vote
5 comments
Rate Comments: Nested

Algebraic Enigma (September 2025 Challenge Question)

Posted August 31, 2025 12:00 AM
Pathfinder Tags: challenge question

The solution of this little problem, set by Dr Puzzlewitz on his blackboard to test the powers of his young pupils—“What are the values of A and B, when 4 is the result of dividing A by B, or of subtracting B from A?”—

  • A - B = 4
  • A ÷ B = 4

Answer, updated 9.23.25
A = 51⁄3 and B = 11⁄3.

Reply

Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Good Answers:

These comments received enough positive votes to make them "good answers".

"Almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!
2
Randall
Guru

Join Date: Aug 2005
Location: Hemel Hempstead, UK
Posts: 5826
Good Answers: 322
#1

Re: Algabraic Enigma (September 2025 Challenge Question)

08/31/2025 4:18 AM

A=16/3

B=4/3

__________________
 If you spend all your time looking for people and things to complain about: trust me, you will find plenty to complain about.
Reply Good Answer (Score 2)
Go to Next Good Answer
tkot
Power-User
Hobbies - Musician - guitar fan Greece - Member - Engineering Fields - Software Engineering -

Join Date: Jul 2007
Location: Athens, Greece
Posts: 256
Good Answers: 18
#2

Re: Algabraic Enigma (September 2025 Challenge Question)

09/01/2025 3:26 AM

Where is the catch? Maybe the choice of the word "or" instead of "and" to combine the two inputs? If yes, then all these are solutions:

1. From A-B=4:

A=4, B=0

A=4.001, b=0.001

... (infinite possibilities)

2. From A/B=4

A=4, B=1

A=40, B=10

... (infinite possibilities)

__________________
 tkot
Reply
3
Alex. Roman
Power-User

Join Date: Oct 2011
Posts: 138
Good Answers: 21
#3

Re: Algabraic Enigma (September 2025 Challenge Question)

09/01/2025 5:44 AM

A ÷ B = 4 Þ A = 4 * B

A – B = 4 * B – B = 3 * B = 4 Þ B = 4/3, A = 16/3
Reply Good Answer (Score 3)
No more Good Answers. Go to first "Almost" Good Answer
steve45
Power-User

Join Date: Apr 2007
Posts: 273
Good Answers: 12
#4
In reply to #3

Re: Algabraic Enigma (September 2025 Challenge Question)

09/02/2025 12:02 PM

I figured it would be a whole number, but it's a fraction.

I got 16/3 and 4/3, like everybody else.
Reply Score 1 for Good Answer
No more "Almost" Good Answers.
richardwagner
Participant

Join Date: Sep 2025
Posts: 1
#5

Re: Algebraic Enigma (September 2025 Challenge Question)

09/23/2025 11:58 AM

A=5.33

B=1.33
Reply Off Topic (Score 5)
Reply to Blog Entry
Have a Different Question?
5 comments

Good Answers:

These comments received enough positive votes to make them "good answers".

"Almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!
Copy to Clipboard

Users who posted comments:

Alex. Roman (1); Randall (1); richardwagner (1); steve45 (1); tkot (1)

Previous in Blog: 10 Questions to Find a Number (August 2025 Challenge Question)   Next in Blog: Steam Train Showtime (Oct. 2025 Challenge Question)

Advertisement

Got Something to Say?
Ask a Question
Start a Discussion

Search this Section
General Discussion:
Go

Search this Blog
Challenge Questions:
Go

Recent Blog Entries

CR4 Sections
Aerospace
BioMech & BioMed
Chemical & Material Science
Civil Engineering
Communications & Electronics
Education and Engineering Careers
Electrical Engineering
General Discussion
Instrumentation
Manufacturing
Mechanical Engineering
New Technologies & Research
Software & Programming
Sustainable Engineering
Transportation

Site Directories
Forum Directory
Blog Directory
User Group Directory
RSS Feeds

CR4 Rules of Conduct
CR4 FAQ
Site Glossary

Who's Online (56 right now)
Show Members
Advertisement