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⏰ 7th grade math · Measure, Time & Money

Circles: around and inside

Circumference is the distance around. C = π × d, and the diameter is twice the radius, so C = 2 × π × r. Example: d = 10 cm gives C = 3.14 × 10 = 31.4 cm. We use 3.14 for π.

Worked example

A circular pond has a diameter of 2 m. What is its circumference? Use 3.14 for π.
d = 2 m
Answer: 6.28 m
Circumference = π × diameter = 3.14 × 2 = 6.28 m.

For grown-ups: Circle circumference and area. Below: three problems to try with the worked answers, and a free printable sheet. Children can practise the same skill as a game, with no sign-up and no ads.

  • CCSS 7.G.B.4
What this practises, for teachers

Practices circle circumference and area (7.G.B.4). A printable sheet with its answer key, worked answers on the page, no accounts.

▶ Practise it

For your class

🖨️ Printable sheet and key

Try three

  1. A circular rug has a diameter of 7 m. What is its circumference? Use 3.14 for π.
    d = 7 m
    Show the answer and how
    Answer: 21.98 m
    Circumference = π × diameter = 3.14 × 7 = 21.98 m.
  2. A circular garden has a radius of 1 m. What is its circumference? Use 3.14 for π.
    r = 1 m
    Show the answer and how
    Answer: 6.28 m
    Circumference = 2 × π × radius = 2 × 3.14 × 1 = 6.28 m. (The diameter is 2, and 3.14 × 2 is the same.)
  3. A circular garden has a circumference of 69.08 m. What is its radius? Use 3.14 for π.
    C = 69.08 m
    Show the answer and how
    Answer: 11 m
    Circumference = 2 × 3.14 × radius, so radius = 69.08 ÷ 6.28 = 11 m.

Before and after

Learn first: Area of triangles and nets (6th)

Comes next: Cylinders, cones and spheres (8th)

Name: ____________________Date: ____________Score: ____ / 12

Circles: around and inside (7th grade)

  1. A circular rug has a diameter of 5 ft. What is its circumference? Use 3.14 for π.
    d = 5 ft
  2. A circle has a diameter of 8 ft. What is its circumference? Use 3.14 for π.
    d = 8 ft
  3. A round table has a radius of 3 ft. What is its circumference? Use 3.14 for π.
    r = 3 ft
  4. A circular garden has a radius of 6 ft. What is its circumference? Use 3.14 for π.
    r = 6 ft
  5. A round pizza has a radius of 10 in. What is its circumference? Use 3.14 for π.
    r = 10 in
  6. A circular pond has a radius of 9 m. What is its circumference? Use 3.14 for π.
    r = 9 m
  7. A round table has a diameter of 6 ft. What is its circumference? Use 3.14 for π.
    d = 6 ft
  8. A round clock has a circumference of 87.92 in. What is its diameter? Use 3.14 for π.
    C = 87.92 in
  9. A round table has a circumference of 56.52 ft. What is its diameter? Use 3.14 for π.
    C = 56.52 ft
  10. A bicycle wheel has a radius of 12 cm. What is its circumference? Use 3.14 for π.
    r = 12 cm
  11. A round pizza has a diameter of 7 in. What is its circumference? Use 3.14 for π.
    d = 7 in
  12. A circle has a circumference of 119.32 cm. What is its radius? Use 3.14 for π.
    C = 119.32 cm

Answer key

  1. 15.7 ft
  2. 25.12 ft
  3. 18.84 ft
  4. 37.68 ft
  5. 62.8 in
  6. 56.52 m
  7. 18.84 ft
  8. 28 in
  9. 18 ft
  10. 75.36 cm
  11. 21.98 in
  12. 19 cm

More 7th grade skills: all 7th grade math skills, or every grade at math skills.