Challenges: Final Friday Fix: October 2018 Challenge

On the final Friday of each month, we’re going to set an Excel challenge for you to puzzle over so that you can get your “Excel fix”. Challenge your office colleagues to see who can solve the puzzle quickest. There’s no prizes at this stage, you’re playing for bragging rights only!

This problem might not seem relevant to the workplace on first glance but bear with me. Our discussion on Monday will explain why I have selected this problem and further, the issues of simply taking everything at face value. But more on that on Monday.

A Prime Example

A positive integer (whole number) is said to be prime if and only if two different integers divide it: one (1) and itself. Therefore, 1 is not prime and 2 is the only even prime etc.

Prime numbers are useful for scenario analysis, public key encryption, reconciliation tricks and Final Friday Fixes.

The Challenge

It’s very simple this month:

Write a formula in Excel to determine whether a number typed in (as above) is prime or not.  That’s it – just no VBA (or JavaScript!) / user defined functions. 

And by the way, if you decide to interrogate the internet, don’t be surprised if you find an answer in 1.2 picoseconds.  Just ask yourself this: we always try to put up challenges that Google somewhat struggles with – so are you sure your solution you “discovered” actually works..?

Sound easy?  Have a go.  We’ll publish a couple of solutions in Monday’s blog.  Have a great weekend!