This grade 3 area worksheet answer key solves all 22 problems of the area worksheet step by step.
Full worked solutions for all 22 area problems. Each answer shows the multiplication sentence or the split into rectangles, so students can find exactly where a mistake happened and fix it.
Grade 3 Area Worksheet Answer Key: problems 1–5
Problem 1: Count the unit squares
There are 3 rows with 5 squares in each row. Count: 5, 10, 15. Or multiply: \(3 \times 5 = 15\).
The area is 15 square centimeters.
Problem 2: Rows and columns
There are 4 rows and 7 columns, so \(4 \times 7 = 28\).
The area is 28 square inches.
Problem 3: Tiles in rows
4 rows of 6 tiles: \(4 \times 6 = 24\).
The area is 24 square feet.
Problem 4: Compare two shapes
Shape A: \(3 \times 4 = 12\) square units. Shape B: split into a 5 by 2 rectangle and a 2 by 1 rectangle, so \(10 + 2 = 12\) square units.
Both areas are 12, so yes, the shapes have the same area (12 square units).
Problem 5: Multiply to find area
\(8 \times 3 = 24\).
The area is 24 square feet.
Grade 3 Area Worksheet Answer Key: problems 6–10
Problem 6: Garden in square meters
\(9 \times 5 = 45\).
The area is 45 square meters.
Problem 7: Area of a square
A square has equal sides, so \(7 \times 7 = 49\).
The area is 49 square inches.
Problem 8: Labeled rectangle
\(12 \times 4 = 48\).
The area is 48 square centimeters.
Problem 9: Missing width
Think: \(9 \times ? = 36\). Since \(9 \times 4 = 36\), the width is 4 inches.
The width is 4 inches.
Problem 10: Missing length
Think: \(7 \times ? = 56\). Since \(7 \times 8 = 56\), the length is 8 feet.
The length is 8 feet.
Grade 3 Area Worksheet Answer Key: problems 11–15
Problem 11: Break apart a rectangle
Left part: \(6 \times 5 = 30\). Right part: \(6 \times 3 = 18\).
Add the parts: \(30 + 18 = 48\).
The whole area is 48 square units. Check: \(6 \times 8 = 48\).
Problem 12: Break apart a factor
\(7 \times 9 = 7 \times (5 + 4)\).
\(7 \times 5 = 35\) and \(7 \times 4 = 28\), so \(35 + 28 = 63\).
The product is 63.
Problem 13: Write the area as a sum
\(5 \times 12 = (5 \times 10) + (5 \times 2)\).
\(50 + 10 = 60\).
The area is 60 square feet.
Problem 14: L-shaped room
Split the room into rectangle A (top, 2 ft by 3 ft) and rectangle B (bottom, 6 ft by 2 ft). The top part is \(5 – 2 = 3\) ft tall.
\(2 \times 3 = 6\) and \(6 \times 2 = 12\).
\(6 + 12 = 18\).
The area is 18 square feet.
Problem 15: T-shaped sign
Split the sign into the top bar and the stem.
Top bar: \(7 \times 2 = 14\). Stem: \(3 \times 4 = 12\).
\(14 + 12 = 26\).
The area is 26 square inches.
Grade 3 Area Worksheet Answer Key: problems 16–20
Problem 16: Floor tiles
\(10 \times 8 = 80\).
She needs 80 tiles.
Problem 17: Store and closet
Main room: \(8 \times 6 = 48\). Closet: \(4 \times 3 = 12\).
\(48 + 12 = 60\).
The total floor area is 60 square feet.
Problem 18: Whose rug is bigger?
Priya: \(6 \times 4 = 24\) sq ft. Diego: \(5 \times 5 = 25\) sq ft.
Compare: \(25 > 24\). The difference is \(25 – 24 = 1\).
Diego’s rug covers 1 square foot more.
Problem 19: Backyard in two parts
Adding: \(9 \times 6 = 54\) and \(4 \times 6 = 24\), so \(54 + 24 = 78\).
One big rectangle: the width is \(9 + 4 = 13\) feet, so \(6 \times 13 = 78\).
Both ways give 78 square feet.
Problem 20: Store sign
First rectangle: \(10 \times 4 = 40\). Second rectangle: \(6 \times 3 = 18\).
\(40 + 18 = 58\).
The total area is 58 square inches.
Grade 3 Area Worksheet Answer Key: problems 21–22
Problem 21: Find the mistake
Noah added the side lengths: \(7 + 6 = 13\). Area is the number of unit squares that cover the rectangle, so he should multiply.
\(7 \times 6 = 42\).
The correct area is 42 square units.
Problem 22: Same area, different rectangles
Find the pairs of whole numbers that multiply to 12: \(1 \times 12\), \(2 \times 6\), \(3 \times 4\).
There are 3 rectangles: 1 by 12, 2 by 6 and 3 by 4.
How to use this grade 3 area worksheet answer key
Read this grade 3 area worksheet answer key after trying each problem yourself, and redo any problem you missed.
See every chapter on the Grade 3 math page.