Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 978 · 40 sums

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.

1. 1.Which of these is a perfect cube? (a) 104 (b) 84 (c) 64
2. 2.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
3. 3.What is ∛2744? =
4. 4.What is ∛15625? =
5. 5.Which of these is a perfect cube? (a) 3833 (b) 3824 (c) 3375
6. 6.What is 6³? =
7. 7.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
8. 8.What is ∛27? =
9. 9.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
10. 10.What is 17³? =
11. 11.Which of these is a perfect cube? (a) 412 (b) 343 (c) 370
12. 12.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
13. 13.What is 15³? =
14. 14.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
15. 15.What is 11³? =
16. 16.What is ∛1000? =
17. 17.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
18. 18.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
19. 19.What is ∛6859? =
20. 20.What is ∛512? =
21. 21.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
22. 22.What is ∛8? =
23. 23.What is 7³? =
24. 24.What is the smallest whole number by which 54 must be divided to get a perfect cube?
25. 25.What is the smallest whole number by which 3136 must be divided to get a perfect cube?
26. 26.What is 4³? =
27. 27.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
28. 28.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
29. 29.What is ∛343? =
30. 30.What is 13³? =
31. 31.What is 18³? =
32. 32.Which of these is a perfect cube? (a) 616 (b) 512 (c) 591
33. 33.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?
34. 34.What is the smallest whole number by which 192 must be multiplied to get a perfect cube?
35. 35.What is ∛125? =
36. 36.What is the smallest whole number by which 54 must be multiplied to get a perfect cube?
37. 37.What is the smallest whole number by which 675 must be multiplied to get a perfect cube?
38. 38.What is 12³? =
39. 39.What is ∛1728? =
40. 40.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?

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