Grade 3 Math · Spatial Sense

Find a missing side length from the perimeter

Given the perimeter and some known side lengths, find a missing side length of a polygon. Unlimited questions, five difficulty levels, and a full worked solution every time — free.

Practice this skill Curriculum: G3-E2.1

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A rectangle has a perimeter of 16 cm and a width of 2 cm. What is its length?

Answer: 6 cm

See one solved, step by step

A rectangle has a perimeter of 14 m and a length of 5 m. What is its width?

📘 Worked solution
114 / 2 = 7Half the perimeter equals one length plus one width.
27 - 5 = 2Subtract the length you know to find the width.

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