Build confidence with printable compound cuboid volume worksheets and focused maths practice tests. Students learn to split stacked solids into cuboids, subtract cut-out sections, and find missing dimensions while improving accuracy with multi-step 3D shape problems.
For students who know length × width × height, but need practice applying it to more complex 3D shapes.
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Students are given 3D composite shapes made from rectangular prisms and must find the total volume or an unknown side length. Questions often involve splitting stacked blocks or subtracting a missing cut-out section to calculate the correct measurement. Here is a worked example.
Question: A 4 cm × 2 cm × 4 cm cuboid sits on a 9 cm × 2 cm × 4 cm cuboid. What is the total volume?
Step 1: Bottom cuboid = 9 × 2 × 4 = 72 cm³.
Step 2: Top cuboid = 4 × 2 × 4 = 32 cm³.
Step 3: Total volume = 72 + 32 = 104 cm³.
Tip: Split a stacked shape into separate cuboids and add their volumes. Do not count an overlapping region twice.
As shown in the example above, breaking a compound 3D solid into simple rectangular blocks makes finding total volume straightforward. Use these core rules to approach stacked shapes, cut-outs, and missing measurements systematically.
Calculate each rectangular block separately before combining the results.
Example: A 9 cm × 2 cm × 4 cm block has volume 72 cm³.
For a stepped or stacked shape, add the volume of each non-overlapping cuboid.
Example: 32 cm³ + 72 cm³ = 104 cm³.
When a corner is removed, calculate the full outer cuboid and subtract the missing block.
Example: 140 cm³ − 24 cm³ = 116 cm³.
For a missing cut-out height, find the removed volume and divide by the cut-out's width × depth. For an unknown shared depth, divide the remaining solid's volume by its remaining front-face area.
Example: 72 cm³ ÷ 36 cm² = 2 cm.
Practise finding volume by subtracting a cut-out corner, then learn how to work backwards from a known volume to find a missing height.
Question: A cuboid is 7 cm wide, 5 cm high, and 4 cm deep. A corner is removed through its full depth, leaving an upper ledge 4 cm wide. The cut-out is 2 cm high. What volume remains?
Step 1: Full cuboid = 7 × 5 × 4 = 140 cm³.
Step 2: Cut-out width = total width − upper ledge width = 7 − 4 = 3 cm.
Step 3: Cut-out cuboid = 3 × 2 × 4 = 24 cm³.
Step 4: Remaining volume = 140 − 24 = 116 cm³.
Tip: Subtraction works well when the shape is easiest to see as one complete cuboid with a corner missing.
Question: A cuboid is 10 cm wide, 7 cm high, and 6 cm deep. A corner is removed through its full depth, leaving an upper ledge 4 cm wide. The remaining volume is 348 cm³. Find the cut-out's missing height, x.
Step 1: Full cuboid = 10 × 7 × 6 = 420 cm³.
Step 2: Cut-out volume = 420 − 348 = 72 cm³.
Step 3: Cut-out width = total width − upper ledge width = 10 − 4 = 6 cm.
Step 4: Cut-out base area = width × depth = 6 × 6 = 36 cm².
Step 5: Divide the removed volume by its base area: x = 72 ÷ 36 = 2 cm.
Answer: x = 2 cm.
Tip: Use the removed 72 cm³ when finding the cut-out height. Dividing the remaining 348 cm³ by the cut-out base area mixes measurements from different solids.