Counting prime numbers in an interval with Excel

Scenario
Suppose you are asked to find out number of prime numbers in an interval.

Suppose lower limit of a range is entered in cell C2 and upper limit in cell C3.

Solution

1. Press CTRL + F3 to open name manager
2. Click "New"
3. In "Name", type rng
4. In "Refers to: " box, enter =ROW(INDIRECT(Sheet1!$C$2&":"&Sheet1!$C$3))

5. Click OK
6. Click Close

In cell E5, enter the following formula :

=SUM(IF(MMULT(--(IF(rng>TRANSPOSE(rng-C2+2),MOD(rng,(rng>TRANSPOSE(rng-C2+2))*TRANSPOSE(rng-C2+2)))=0),rng-C2+2)=0,1))

Hit CTRL + SHIFT + ENTER to confirm this formula as an array formula. If done correctly, Excel will automatically place curly braces {...} around the formula.

Download the workbook

Related Post :
Generating prime numbers in an interval with Excel
Check if a number is prime with Excel

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About Author:
Deepanshu Bhalla

Deepanshu founded ListenData with a simple objective - Make analytics easy to understand and follow. He has over 10 years of experience in data science. During his tenure, he has worked with global clients in various domains like Banking, Insurance, Private Equity, Telecom and Human Resource.

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1 Response to "Counting prime numbers in an interval with Excel"

robAugust 15, 2020 at 7:13 AM
Great stuff! Thanks for posting... I love to see how things work... Also, I like to see how far you can push Excel before it breaks. I expanded the list of primes from 25 to 500, runs slow but still works.