#### How to handle prime numbers in Excel

In this Excel tutorial, you can learn how to handle prime numbers in Excel.

You can create a formula to determine if a number is prime. Here’s a workaround using Excel functions to handle prime numbers:

### Method 1: Using an Array Formula to Check for Prime Numbers

You can create a custom formula to check if a number is prime by using an array formula that utilizes the MOD function and a logical test. Here’s how to do it:

1. Type the numbers you want to check in a column, say column A, starting from A2.
2. Label it “Is Prime?” in column B.
3. Enter the following array formula to check if A2 is a prime number: =IF(A2<2, “No”, IF(AND(MOD(A2, ROW(INDIRECT(“2:”&INT(A2/2))))<>0), “Yes”, “No”))

After typing the formula, instead of just pressing Enter, you need to press Ctrl + Shift + Enter. Excel will enclose the formula in curly braces {}, indicating it’s an array formula.

Drag the fill handle (or double-click it) to copy the formula down to other cells in column B.

This formula works by checking if the number is divisible by any number from 2 up to half of its value (since a number cannot be divided by more than its half to yield a whole number). If it finds no divisors, it returns “Yes” to indicate the number is prime.

### Method 2: Using Conditional Formatting to Highlight Prime Numbers

Another approach to handle prime numbers in Excel is by using conditional formatting to visually highlight them:

1. Select your data range in column A.
2. Go to the Home tab, click on Conditional Formatting, and choose New Rule.
3. Select Use a formula to determine which cells to format.
4. Enter the array formula (the same as above without the IF part to check for prime numbers): =AND(A2>1, MOD(A2, ROW(INDIRECT(“2:”&INT(A2/2))))<>0)
5. Set a format (e.g., a fill color).