Worksheet Cube - 1 | Mental Mathematics for Class 8 PDF Download

Q1: Which of the following numbers is a perfect cube?
(a) 256
(b) 243
(c) 1331
(d) 250

Q2: What will be the volume of a cube having edge length 12m? (in m³)
(a) 1728
(b) 1628
(c) 2248
(d) 1848Q3: What is the smallest number by which 576 is divided that quotient is a perfect cube?
(a) 8
(b) 9
(c) 4
(d) 72

Q4: If, 1³ + 2³ + 3³ = (1 + 2 + 3)², 1³ + 2³ + 3³ + 4³ = (1 + 2 + 3 + 4)², then, 1³ + 2³ + 3³ + 4³ + 5³ + 6³ + 7³
(a) 900
(b) 441
(c) 784
(d) 484

Q5: Observing the pattern 1³ + 2³ + 3³ = (1 + 2 + 3)², 1³ + 2³ + 3³ + 4³ = (1 + 2 + 3 + 4)² , Find the sum: 1³ + 3³ + 5³ + 7³ + 9³
(a) 1225
(b) 2025
(c) 825
(d) 1625

Q6: Simplify : (a) 400(b) 8000
(c) 64000
(d) 512000

Q7: Simplify: (64/125)^2/3
(a) 4/5
(b) 8/25
(c) 16/25
(d) 4/25

Q8: A natural number is of the form (3n + 2). Its cube will be of the form :
(a) 3n
(b) 3n + 1
(c) 3n + 2
(d) None of these

Q9: A rational number, p < 1, then,
(a) p³ > 1
(b) p³ < 0
(c) p³ < p
(d) p³ > p

Q10: A real number ‘p’ is such that p > 1, then
(a) p³ < 1
(b) p³ > p
(c) p³ < p
(d) p³ <  0

Q.11: Find the cube of 3.5.

Q.12: Find the smallest number by which 128 must be divided to obtain a perfect cube.

Q.13: Find the cube root of 13824 by prime factorisation method.

Q.14: Is 392 a perfect cube? If not, find the smallest natural number by which 392 should be multiplied so that the product is a perfect cube.

Q.15: Parikshit makes a cuboid of plasticine of sides 5 cm, 2 cm, 5 cm. How many such cuboids will he need to form a cube?