“For each.” According to; by.
In math, the word per means “for each” or “for every.” It’s often used when talking about rates or ratios, which are some of the ways to compare two quantities.
For example:
- If we drive 60 miles every 1 hour, we say we’re going 60 miles per hour.
- If pencils cost $2 each, we say they cost $2 per pencil.
The word “per” helps us understand how much of one thing there is for each of another. It signals a comparison between two quantities, often found by dividing one quantity by another.
We often see “per” in:
- Unit rates (like miles per hour or dollars per item)
- Word problems
- Real-life math situations involving prices, speed, or measurements
And, you may have guessed it: We see “per” in “percent!” We already know what “per” is and “cent” simply means “hundred,” so “percent” indicates a certain quantity for every hundred units.
When Do Students Learn About "Per"?
Students formally use the word "per" as part of understanding rates and ratios, usually in upper elementary and middle school.
Grades 4–5 – Introduction to Rates
Students begin exploring simple ratios and unit prices using “per.”
Grades 6+ – Working with Unit Rates and Proportional Reasoning
Students apply “per” in a variety of contexts, including speed, density, pricing, and more.
