7th Grade · Geometry
Pi
7.G.B.4
Definition
The ratio of a circle's circumference to its diameter. π ≈ 3.14. It is an irrational number — it never terminates or repeats. Used in circle formulas.
Examples
- π is the same for every circle, no matter the size.
- π ≈ 3.14 for calculations, or 22/7 as a fraction approximation.
Key rule
π cannot be written as an exact fraction or decimal — we always use an approximation.
Memory hook
Same ratio, every circle, forever.