Understanding the ISODD Formula

The ISODD function in Excel checks whether a number is odd, returning TRUE if odd and FALSE if even. It's a number classification tool for data analysis—like sorting data into alternating groups or performing different calculations based on whether a value is divisible by 2 with a remainder.

ISODD(3) evaluates the number 3 and returns TRUE because it's an odd number. It takes a number argument, rounds toward zero if necessary, and tests for a remainder when divided by 2—useful for conditional formatting or when creating formulas that need to behave differently for odd versus even values.

Why Use ISODD?

ISODD enables parity checking—think alternating calculations or formatting. Its simple TRUE/FALSE determination makes it ideal for creating striped reports, handling special cases in position-based operations, or implementing algorithms that depend on whether indices or counts are odd or even.

Example with Sample Data

ISODD determines number parity: TRUE for 3, 5, -7, etc. (not divisible evenly by 2), FALSE for 4, 0, -2, etc. (divisible evenly by 2). When used with conditional formatting, it can create alternating row colors in tables. It's an oddness checker.