A couple or (of) them went the other way

People often write or say "or" when they mean "of." That swap breaks phrases that show quantity, membership, or relationship (a couple of, a pair of, a number of). Below: a short rule, clear examples for work/school/casual writing, ready-to-paste rewrites, quick editing checks, and a simple memory trick.

Quick answer

Use of to show relationship, quantity, or membership (a couple of them; a pair of shoes). Use or to present alternatives (tea or coffee). If the phrase answers "which ones" or "how many" within a group, use of-not or.

Of = preposition for relationships, parts and quantities (a number of students).
Or = conjunction for choices and alternatives (this or that).
If swapping the word breaks the relationship in the phrase, choose of.

Core rule (short and actionable)

If a noun phrase names part of a set, a quantity, or belonging, use of. Typical patterns: a couple of, a pair of, a group of, a number of, one of the, none of the.

Or connects alternatives and never marks membership or quantity. Swapping of with or usually makes the phrase ungrammatical.

Quantity/membership → of (a couple of friends; two of those files).
Alternatives/choice → or (apples or oranges).
Test: if you can insert "part of" or "belonging to" and the sentence still reads, use of.

Wrong: A couple or them went the other way.
Right: A couple of them went the other way.
Wrong: She brought a pair or shoes.
Right: She brought a pair of shoes.
Wrong: Two or my colleagues are on PTO.
Right: Two of my colleagues are on PTO.

Real usage and tone: when people omit 'of' and when to keep it

In casual speech people sometimes drop of (I saw a couple people). That's common in conversation but not standard in formal writing.

Work/formal: always use of (emails, reports, resumes, essays).
Casual speech/texts: omission occurs, but it's stylistic-avoid it in writing meant for others.
If your audience includes non-native speakers or formal readers, keep of for clarity.

Casual: I saw a couple people at the cafe. (common in speech)
Formal: I saw a couple of people at the cafe. (recommended for writing)

Examples: work, school and casual (wrong → right)

Use these as quick find-and-replace edits in drafts. Each pair highlights the short phrases that often trigger the error.

Work

Wrong: Two or the reports are missing.
Right: Two of the reports are missing.
Wrong: A number or employees asked for remote work.
Right: A number of employees asked for remote work.
Wrong: Please review a couple or the slides.
Right: Please review a couple of the slides.

School

Wrong: One or the students submitted late.
Right: One of the students submitted late.
Wrong: A couple or assignments were incomplete.
Right: A couple of assignments were incomplete.
Wrong: Two or chapters cover the topic.
Right: Two of the chapters cover the topic.

Casual

Wrong: I invited a couple or friends to dinner.
Right: I invited a couple of friends to dinner.
Wrong: She lost a pair or gloves.
Right: She lost a pair of gloves.
Wrong: A bunch or people showed up.
Right: A bunch of people showed up.

How to rewrite: quick fixes and better alternatives

Fixes fall into three moves: swap the word, replace the phrase with a specific number, or restructure the sentence for flow.

Swap: Change or → of when the phrase shows membership or quantity.
Replace: Use a specific number (two, several, many) to avoid fuzzy phrases.
Restructure: Turn the phrase into a clearer clause when it reads awkwardly.

Rewrite - swap: Wrong: A couple or them left early. Swap: A couple of them left early.
Rewrite - replace: Wrong: We invited a couple or friends. Better: We invited two friends.
Rewrite - restructure: Wrong: Give me two or those. Better: Give me two of those / Please hand me those two.
Additional: Wrong: A pair or gloves was missing. Swap: A pair of gloves was missing. Or more natural: One glove from the pair was missing.

Try your own sentence

Test the whole sentence, not just the phrase. Context usually makes the right choice clear.

Memory trick and editing hacks

Mnemonic: O-F = Of = Owned / Of = shows relationship. O-R = Or = Option / Or = shows choice. If the phrase names part of a set, pick O-F.

Editing hacks: search your draft for common triggers and read flagged lines aloud before accepting fixes.

Search for exact patterns: "a couple or", "a pair or", "a number or", "one or the", "none or the".
Read aloud: if it sounds like you're naming members of a set, use of.
Add phrases you personally mistype to a custom search list.
Search-and-fix: Find "a couple or" → change to "a couple of" then read the sentence for tone.

Similar mistakes and quick fixes

People who swap or/of often make other short-word errors. Fix these in the same proofreading pass to clean your draft quickly.

In regard to (preferred) not "in regards to".
A lot of (correct) - watch for accidental "a lot or".
Number of vs amount of: use "number of" for countables, "amount of" for uncountables.

Wrong: He gave a lot or reasons for leaving.
Right: He gave a lot of reasons for leaving.
Wrong: In regards to your question, we will follow up.
Right: In regard to your question, we will follow up.
Wrong: The amount of students in the class was large.
Right: The number of students in the class was large.

Spacing, hyphenation and punctuation notes

This error is nearly always a wrong word choice, not a spacing or hyphen issue. Still, fast typing can create similar-looking typos.

No hyphen: "a couple of", "a pair of", "a number of".
Watch fast-typing typos (e.g., "a couple r them" or "Two ofmy friends").
Commas and parentheses don't change whether you should use of or or.

Typo: "A couple r them" → correct: "A couple of them".

Grammar deep dive (brief)

"Of" is a preposition that links nouns to show relationships (possession, part, origin). In "a pair of shoes," the pair relates to the shoes-"of" signals that relation.

"Or" is a coordinating conjunction that joins alternatives; it cannot create a noun-to-noun relationship. Replacing of with or forces a conjunction where a preposition is required, so the phrase collapses grammatically.

Try inserting "belonging to" or "part of"-if it fits, use of.
If a quantifier (a couple ___) expects a preposition, the correct choice is usually of.
Usage: "Two of my friends" = "two belonging to my friends" → of is correct; "two or my friends" is wrong because it implies a choice.

FAQ

When should I use or vs of?

Use of for relationships, possession and quantities (a couple of, a pair of). Use or when offering a choice between items (this or that). If the phrase describes part of a set, choose of.

Is "a couple people" acceptable?

In casual speech many native speakers say "a couple people," but in standard written English you should write "a couple of people." Use the full form in formal writing.

Why do writers type "or" instead of "of"?

Mostly fast typing, adjacent-key slips, or thinking in spoken fragments. Both words are short, so they're easy to substitute accidentally.

Will grammar checkers find this error?

Many grammar checkers flag patterns like "a couple or" or "a pair or." They catch most instances, but inspect suggested rewrites-sometimes rephrasing is a better fix than a straight swap.

How do I fix "A number or students missed class"?

Replace or with of: "A number of students missed class." Or rephrase: "Many students missed class."

Want to check one sentence quickly?

When editing, paste a suspect sentence into a checker or run a quick search for the patterns listed above. A short custom search list of the phrases you mistype most (for many people: "a couple or", "a pair or", "a number or") saves embarrassing slips in emails, assignments, and posts.