Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 773 · 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.What is the smallest whole number by which 392 must be divided to get a perfect cube?
2. 2.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
3. 3.Which of these is a perfect cube? (a) 2744 (b) 2837 (c) 3116
4. 4.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
5. 5.What is the smallest whole number by which 675 must be multiplied to get a perfect cube?
6. 6.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
7. 7.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
8. 8.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
9. 9.What is 12³? =
10. 10.Which of these is a perfect cube? (a) 285 (b) 229 (c) 216
11. 11.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
12. 12.Which of these is a perfect cube? (a) 2109 (b) 1728 (c) 2084
13. 13.What is the smallest whole number by which 1600 must be divided to get a perfect cube?
14. 14.What is the smallest whole number by which 3 must be divided to get a perfect cube?
15. 15.What is the smallest whole number by which 500 must be divided to get a perfect cube?
16. 16.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
17. 17.What is ∛4096? =
18. 18.What is ∛216? =
19. 19.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
20. 20.What is 13³? =
21. 21.What is the smallest whole number by which 675 must be divided to get a perfect cube?
22. 22.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
23. 23.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
24. 24.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
25. 25.What is 17³? =
26. 26.What is the smallest whole number by which 1125 must be divided to get a perfect cube?
27. 27.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
28. 28.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
29. 29.Which of these is a perfect cube? (a) 68 (b) 64 (c) 110
30. 30.What is ∛27? =
31. 31.What is the smallest whole number by which 864 must be divided to get a perfect cube?
32. 32.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?
33. 33.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
34. 34.What is the smallest whole number by which 189 must be multiplied to get a perfect cube?
35. 35.Which of these is a perfect cube? (a) 904 (b) 729 (c) 849
36. 36.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
37. 37.Which of these is a perfect cube? (a) 2197 (b) 2437 (c) 2254
38. 38.What is 6³? =
39. 39.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
40. 40.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?

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