Class 8 Maths Worksheet: Cubes and Cube Roots
The method (Threes make cubes): Cube: n × n × n. Cube root: the number that, used three times, gives the cube. Units digits: 1→1, 2→8, 3→7, 4→4, 5→5, 6→6, 7→3, 8→2, 9→9, 0→0 — use them to guess cube roots. Make a perfect cube: break into primes; multiply by what completes each group of three (or divide by what is left over). A big cube of edge a cut into small cubes of edge b gives (a ÷ b)³ small cubes.
NameDateTime takenScore ___ / 40
- 1.What is ∛216? =
- 2.What is the smallest whole number by which 54 must be divided to get a perfect cube?
- 3.What is the smallest whole number by which 128 must be multiplied to get a perfect cube?
- 4.Which of these is a perfect cube? (a) 2197 (b) 2207 (c) 2405
- 5.What is ∛2744? =
- 6.Which of these is a perfect cube? (a) 133 (b) 125 (c) 181
- 7.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
- 8.What is ∛8000? =
- 9.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
- 10.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
- 11.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
- 12.What is 12³? =
- 13.What is ∛343? =
- 14.What is ∛12167? =
- 15.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
- 16.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
- 17.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
- 18.What is ∛1000? =
- 19.What is 2³? =
- 20.What is the smallest whole number by which 5400 must be multiplied to get a perfect cube?
- 21.What is the smallest whole number by which 49 must be divided to get a perfect cube?
- 22.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
- 23.What is 19³? =
- 24.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
- 25.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
- 26.Which of these is a perfect cube? (a) 1971 (b) 1807 (c) 1728
- 27.Which of these is a perfect cube? (a) 521 (b) 611 (c) 512
- 28.What is ∛1728? =
- 29.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
- 30.What is 7³? =
- 31.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
- 32.What is ∛9261? =
- 33.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
- 34.What is 13³? =
- 35.What is ∛15625? =
- 36.What is ∛512? =
- 37.What is 14³? =
- 38.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
- 39.What is 10³? =
- 40.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
Answer key
- 6
- 2
- 4
- 2197
- 14
- 125
- 27
- 20
- 20
- 18
- 6
- 1728
- 7
- 23
- 2
- 12
- 125
- 10
- 8
- 5
- 49
- 8
- 6859
- 4
- 15
- 1728
- 512
- 12
- 5
- 343
- 4
- 21
- 27
- 2197
- 25
- 8
- 2744
- 7
- 1000
- 25
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