Kissan S.

asked • 09/11/16

by using only three 5's how can I get answer as 3?

Only these symbols like +, -, /, *,squareroots should be used.

David S.

tutor
Since the topic you chose for this topic was Reasoning (versus Order of Operations, etc.) I'm wondering about how restrictive your math toolkit has to be.  Do you think that the word "only" as a qualifier in both sentences prevents using any other numbers (2, 3, 4, ...) and any other symbols (%, ^, !, etc.)?  I've come up with one way, for now, and I'm checking my assumptions by "thinking outside the box" so to speak.  The symbol (~) is a part of my math toolkit, which seems within the realm of using mathematical reasoning.
Report

09/11/16

2 Answers By Expert Tutors

By:

David S. answered • 09/11/16

Tutor
5.0 (386)

Specializing in Physics, Physical Science, & supporting Math concepts
About this tutor ›
About this tutor ›
Something to consider...  5^0 + 5^0 + 5^0
 
This is worth exactly 3, but requires other numbers and another operation (stretching the rules of "only three 5's" and "only symbols like" a little bit).
 
The other ways I found to get an answer of 3 require rounding of my result to the nearest integer, which might be allowable since this seemed to be a reasoning type of exercise.  
√5+(5/5)= 3.236... ≅ 3
 
Also, "only" could be taken to mean "no more than" three 5's...
√(5+5)= 3.162...   ≅ 3
|(√5-5|= 2.7639... ≅ 3
 
Any other ideas?
 
 
Upvote • 0 Downvote
More
Report

Arthur D.

tutor
David, using the decimal point is very useful in these types of problems.
Report

09/11/16

Still looking for help? Get the right answer, fast.

Ask a question for free

Get a free answer to a quick problem.
Most questions answered within 4 hours.

OR

Find an Online Tutor Now

Choose an expert and meet online. No packages or subscriptions, pay only for the time you need.