I am math-geek-wannabe, if there ever is such a category. During my 3rd year of graduation I went and purchased the volume 2 of Donald Knuth‘s Art of Computer Programming and thus began my love with all things random and prime. I never really became the math-geek I always wanted to, instead I became an insurance expert with tons of passion for data and visualization. But when I get a chance to poke with randomness or numbers, I always lap it up with joy. And that brings us to an interesting array formula trick to check if a number is prime or not.
(assuming the number is in the cell B5) type the below formula and
=IF(MIN(MOD($B$5,ROW(INDIRECT("2:"&INT(SQRT($B$5))))))=0,"not prime","prime")
hit ctrl+shift+enter and bingo, it tells you if the number is prime or not.
how it works?
take a guess…
you are right. It just calculates the minimum of all reminders when the number x is divided by values between 2 and sqrt(x) and sees if it is zero. If so, the number is “not prime”, else, it is a “prime number”.
More random stuff on randomness and numbers
Shuffle a list of values in excel using random numbers

















6 Responses to “A quick personal update”
Thank you for the personal update. It was quite encouraging and a breath of fresh air in my Inbox. Take care and stay safe.
David
Doctors advise:
Virus obstructs lungs with thick mucus that solidifies.
Consume lot hot liquids like tea, soup, and sip of hot liquid every 20 min
Gargle w antiseptic of lemon, vinegar, & hot water daily
It attaches to hair/clothes detergent kills it, when come from st go straight shower
Hang dirty clothes in sunlight/cold overnight or wash immediately.
Wash metal surfaces as it can live on them 9 days
Do not touch hand rails
Do not smoke
Wash hands foaming 20 sec every 20 min
Eat fruit/veg and up zinc levels.
Animals do not spread it
Avoid common flu
Avoid eat/drink cold things
If feel sore throat do above immediate as virus is there 3-4 days before descends into lungs
Would love help with my database mgt in excel.
Thanks for being thoughtful of us.
BTW How do you track your expenses/income in excel? Can you share the worksheet please.
Stay safe you and your family, best wishes.
Thanks for the update and happy to know that you and family are doing good. A 21 day lockdown has now been announced in India (I live around Kolkata) so it's uncertain times ahead. I check up on your wonderful articles often and will do so even more regularly now. Stay safe and God bless.
Hi from Argentina, I follow you for a lot of years now. We here are in a quarantine for 2 or 3 weeks, because the pandemia.
Excel is also my passion and I came here looking for a Num2Words formula, but in spanish. If anyone have it, please let me know.
Best regards.
Pablo Molina
La Rioja - Argentina
I'm glad to have your personal update. I'm from India & following you for so many years. Cheers to have any further personal update.