SME
Grade 3 Math · Measurement & Data
Area and multiplication
Use this for “How many square centimeters cover a rectangle 4 cm by 3 cm?”
Diagram
This is an example. Type your own values to start a new problem.
Length (cm)
×
Width (cm)
=
Area (cm²)
Formulas
4 × 3 = 12
Length × width = area
Assumptions
•
The shape is a rectangle: four right angles, and opposite sides are equal.
•
Length and width use the same unit, so area is in square units.
•
Area counts the unit squares that cover the inside with no gaps or overlaps.
Step-by-step
WE KNOW
Length: 4 cm
Width: 3 cm
FIND
area
Step 1 · Find area
4 × 3 = ?
Length × width = area
The width is the number of rows; the length is the squares in each row. Multiply.
Count by 4s, 3 times: 4, 8, 12 → 12
Area = 12 cm²
Check
Put the numbers back in. Both sides should match.
4 × 3 = 12 ✓
Topic check
See what you know: 5 questions on this topic
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More problem types
Find an unknown side from the area
Use this when you know the area and one side: “24 cm², 6 cm long. How wide?”
Area and the distributive property
Use this to split a rectangle into two and add the areas: 6 × 8 = 6 × 5 + 6 × 3.
Area of composite figures
Use this to find the area of an L-shape made of two rectangles.
Area of a shape with a corner cut out
Use this for an L-shape: the whole rectangle take away the corner cut out.