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ICSE-VIII-Mathematics

04: Cubes and Cube Roots Class 8 Maths

with Solutions -
Qstn# A-3 Prvs-QstnNext-Qstn
  • #3
    Find the cubes of : (i) 2.1 (ii) 0.4 (iii) 1.6 (iv) 2.5 (v) 0.12 (vi) 0.02 (vii) 0.8
    Ans : (i) 2.1= (2.1)3= (21/10)3= (21 × 21 × 21)/(10 × 10 × 10)
    = 9261/1000
    = 9.261 (ii) 0.4= (0.4)3= (4/10)3= (4 × 4 × 4)/(10 × 10 × 10)
    = 64/1000
    = 0.064 (iii) 1.6= (1.6)3= (16/10)3= (16 × 16 × 16)/(10 × 10 × 10)
    = 4096/1000= 4.096 (iv) 2.5= (2.5)3= (25/10)3= (25 × 25 × 25)/(10 × 10 × 10)= 15625/1000
    = 15.625 (v) 0.12= (0.12)3= (12/100)3= (12 × 12 × 12)/(100 × 100 × 100)
    = 1728/1000000= 0.001728 (vi) 0.02= (0.02)3= (2/100)3= (2 × 2 × 2)/(100 × 100 × 100)
    = 8/1000000= 0.000008 (vii) 0.8= (0.8)3= (8/10)3= (8 × 8 × 8)/(10 × 10 × 10)
    = 512/100
    = 0.512
  • #3-i
    2.1
    Ans : 2.1= (2.1)3= (21/10)3= (21 × 21 × 21)/(10 × 10 × 10)
    = 9261/1000
    = 9.261
  • #3-ii
    0.4
    Ans : 0.4= (0.4)3= (4/10)3= (4 × 4 × 4)/(10 × 10 × 10)
    = 64/1000
    = 0.064
  • #3-iii
    1.6
    Ans : 1.6= (1.6)3= (16/10)3= (16 × 16 × 16)/(10 × 10 × 10)
    = 4096/1000= 4.096
  • #3-iv
    2.5
    Ans : 2.5= (2.5)3= (25/10)3= (25 × 25 × 25)/(10 × 10 × 10)= 15625/1000
    = 15.625
  • #3-v
    0.12
    Ans : 0.12= (0.12)3= (12/100)3= (12 × 12 × 12)/(100 × 100 × 100)
    = 1728/1000000= 0.001728
  • #3-vi
    0.02
    Ans : 0.02= (0.02)3= (2/100)3= (2 × 2 × 2)/(100 × 100 × 100)
    = 8/1000000= 0.000008
  • #3-vii
    0.8
    Ans : 0.8= (0.8)3= (8/10)3= (8 × 8 × 8)/(10 × 10 × 10)
    = 512/100
    = 0.512