Calculating Perimeter
Grade 3 · Math · Area and Perimeter · Pennsylvania, USA
Lesson Summary
You can use addition or shortcuts to find perimeter quickly, especially for rectangles and squares.
Explanation
For a rectangle, opposite sides are the same length. So you can add the length and width and then double that sum: perimeter = 2 × (length + width). For a square, all four sides are equal, so perimeter = 4 × side length. These shortcuts save time. Always remember to include the unit of measurement in your answer.
Practice Questions
Q1: A rectangle is 8 cm long and 3 cm wide. What is its perimeter?
Answer: 22 cm, because 2 × (8 + 3) = 2 × 11 = 22.
Q2: A square has a side length of 9 m. What is its perimeter?
Answer: 36 m, because 4 × 9 = 36.
Q3: A rectangle has a perimeter of 20 cm and a length of 6 cm. What is its width?
Answer: 4 cm, because 20 = 2 × (6 + width), so 10 = 6 + width, width = 4.
People Also Ask
What is Calculating Perimeter in Grade 3 Math?+
Calculating Perimeter is a lesson in the Area and Perimeter chapter of Grade 3 Math. It is part of the Pennsylvania, USA school curriculum and covers key concepts that students need to understand at this level.
What grade level covers Calculating Perimeter?+
Calculating Perimeter is taught in Grade 3 as part of the Math curriculum in Pennsylvania, USA.
How can I help my child with Area and Perimeter in Math?+
Start with the lesson summary and explanation on this page. Practice the questions provided, then use TutorTom for personalized, step-by-step help with Area and Perimeter topics.