The smallest positive integer `n` , for which `864 n` is a perfect cube, is (a) 1 (b) 2 (c) 3 (d) 4

The smallest positive integer n, for which 864n is a perfect cube,is (a) 1 (b) 2 (c) 3 (d) 4

Let P(n): 2^(n) lt n! , then the smallest positive integer for which P(n) is true is: (i) 1 (ii) 2 (iii) 3 (iv) 4