3.MD.7: Relate Area to Multiplication and Addition
Also written as 3.MD.C.7 and CCSS.MATH.CONTENT.3.MD.C.7 · Cluster: Geometric measurement: understand concepts of area and relate area to multiplication and to addition.
The Official Wording
Relate area to the operations of multiplication and addition.
Common Core State Standards, Grade 3, Measurement & Data · Read it at the source · Checked October 14, 2026
What 3.MD.7 Means in Plain English
Third graders tile a rectangle and see the count match the sides multiplied: 6 rows of 8 tiles is 6 × 8 = 48 square feet. Then they multiply without tiling, split a rectangle into 6 × 5 and 6 × 3, and find L-shapes by adding rectangles.
Parts a and b tie area to the times tables (3.OA.7). Part c gives the distributive property (3.OA.5) a picture, and part d makes area additive. In 4th grade the area formula solves for missing sides (4.MD.3), and the split rectangle carries two-digit multiplication (4.NBT.5).
3.MD.7 I Can Statements
- I can show that tiling and multiplying give the same area.
- I can split a rectangle to multiply in two easier parts.
- I can find the area of an L-shape by adding two rectangles.
3.MD.7 Worked Example
A patio laid one square-foot tile at a time, so each row of the array is a row of tiles.
The patio is 6 feet wide and 8 feet long, so it takes 6 × 8 = 48 square feet of tile. Split the 8 into 5 + 3 and the patio becomes two rectangles: 6 × 5 = 30 and 6 × 3 = 18, and 30 + 18 = 48. That split is the distributive property (part c), and adding two rectangles is how an L-shaped patio is measured too (part d).
Common Mistakes with 3.MD.7
Adding the side lengths
A 6 by 8 rectangle given an area of 14
Try this: Tile one rectangle and count the squares, then compare the count with 6 + 8 and with 6 × 8. Only the product matches.
Overlapping pieces of an L-shape
An L-shape split into two rectangles that both include the corner, so those squares are counted twice
Try this: Draw one cut line across the shape and shade the two parts in different colors, so no square belongs to both.
Guessing a missing side
An unlabeled side of an L-shape judged by eye, so a 4-foot piece becomes 5 feet
Try this: Find unlabeled sides from the opposite sides: if the bottom is 10 feet and the top step is 6, the missing piece is 4.
Where 3.MD.7 Fits
Practice 3.MD.7
Quick Check
- A rug is 4 feet wide and 9 feet long. What is its area?
- Find 7 × 8 by splitting the 8 into 5 + 3.
- An L-shaped garden is made of a 6 by 4 foot rectangle and a 3 by 2 foot rectangle that do not overlap. What is its area?