Find the smallest number by which each of the following numbers must be multiplied to obtain a perfect cube: (i) 243 (ii) 256 (iii) 72 (iv) 675 (v) 100

(i) 243 = 3 × 3 × 3 × 3 × 3 = 3^3 × 3 × 3
Required number = 3
(ii) 256 = 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 = 2^3 × 2^3 × 2 × 2
Required number = 2
(iii) 72 = 2 × 2 × 2 × 3 × 3 = 2^3 × 3 × 3
Required number = 3
(iv) 675 = 5 × 5 × 3 × 3 × 3 = 3^3 × 5 × 5
Required number = 5
(v) 100 = 2 × 2 × 5 × 5
Required number = 2 × 5 = 10