ISODD Function in Apple Numbers: Check Whether a Number Is Odd

=ISODD(num)

There is one required argument, with no documented optional parameter or default. Do not call the function without the argument. Apple explicitly says TRUE corresponds to a test value of 1, giving =ISODD(TRUE) TRUE, and FALSE corresponds to 0, giving =ISODD(FALSE) FALSE. These rules are specific official Apple statements, not Excel assumptions.

What is odd? An integer is odd when dividing it by 2 leaves a remainder. An ordinary decimal input is checked after its decimal portion is discarded: 3.75 behaves like 3. This does not test whether a fractional numeric value is itself an integer. Use a separate validation check when integers are required.

In a Numbers table named Alternating Jobs, create header row A1 Job, B1 Job number, C1 Odd?, D1 Assignment. Fill rows 2–9 with these job numbers:

Put in C2 and copy to C9:

=ISODD(B2)

Put in D2 and copy to D9:

=IF(ISODD(B2),"Team A","Team B")

This is suitable for integer job indices, not necessarily real invoice strings or calendar dates. All result cells in the table are expected calculations: Apple directly documents ISODD(3), ISODD(3.75) and ISODD(2); remaining integer cases were independently computed from parity, and native Numbers execution was not performed. The table’s row 6 demonstrates why 3.75 passes an odd check despite not being an integer.

Alternating status flags: =IF(ISODD(B2),"Needs review","Auto-route") labels an integer index differently on every row. Before using a workflow formula, validate that B2 is a number representing the index, and confirm that copy-down references remain inside the right table. A number such as 0 is even, so the first assignment depends on whether your sequence starts at 0 or 1.

Pair with ISEVEN for an audit: A properly numeric integer cannot be both odd and even. Independent logic therefore predicts opposite results for =ISODD(B2) and =ISEVEN(B2). Apple’s pages explicitly describe the opposite parity definitions and Boolean handling (ISODD; ISEVEN). Do not interpret these functions as a full data-quality check: both ignore decimal fractions.

Boolean corner cases: =ISODD(TRUE) is TRUE and =ISODD(FALSE) is FALSE. These are directly documented, and differ from the ISEVEN test’s outputs for the same flags. If your worksheet represents Boolean true/false as text strings, the Apple documentation does not establish that "TRUE" and "FALSE" are equivalent valid arguments.

Negative decimals versus integer rounding: A numerical expression can have fractional digits even when it comes from a whole-number calculation. Apple’s ISODD reference says the fraction is ignored, but Apple’s INT function is a round-down operation and should not be used as a stand-in for fractional truncation in negative cases. Test relevant negative fractions natively rather than inferring device-specific edge rules beyond Apple’s statement.

Apple and Microsoft Excel ISODD both specify one argument and truncation of non-integer numeric inputs. Microsoft’s error text for a nonnumeric Excel argument and Excel-specific coercion rules are not confirmed Apple Numbers behavior. The official Apple entry is from Functions Help 15.4, not proof this function first appeared in Numbers 15.4. For decimal-comma locales enter numbers using the proper decimal mark; ISODD itself only accepts one parameter, so it has no argument separator to change. Other spreadsheet engines have not been natively tested.

Apple ISEVEN for even-number testing; Apple Functions overview for argument syntax; Apple cell references for same-table and cross-sheet formulas.

Apple’s documented examples and TRUE/FALSE behavior were checked on 2026-10-12; remaining table values were independently calculated, not observed in an Apple Numbers app. No native installation testing or application screenshots were performed.

This article was checked against the 15.4 edition of Apple’s Formulas and Functions Help on 2026-10-12. 15.4 is the documentation edition, not a verified first-supported Numbers app release. The function is listed in Apple’s function browser; exact historical release introduction, device-version differences, and behavior of an installed Numbers build were not independently established. Before relying on an older Mac/iPhone/iPad or iCloud copy, confirm the formula is offered in that app’s Function Browser. The Apple function catalogue and function syntax overview are the reference, not another spreadsheet application’s defaults.

Apple’s English examples use a comma between arguments. Where your system uses a comma as decimal separator, Apple’s overview instructs you to type a semicolon as argument separator. The one-argument functions ISEVEN and ISODD have no internal argument separator. For DELTA, =DELTA(2;2) is the comma-decimal-locale equivalent of =DELTA(2,2) in the English examples; use the locale’s decimal mark for fractional numbers. Function names can be entered in mixed case.

Create a normal Numbers table with one header row. Formulas such as =ISEVEN(B2) or =DELTA(B2,C2) refer to cells in that same table. A reference to another table may require Table 2::B2, and another sheet may require Sheet 2::Table 2::B2. Apple’s cell-reference rules document the qualifiers; don’t assume spreadsheet-wide cells without tables as in Excel.