Question

14. By what least number 4320 be multiplied to obtain a number which is a perfect cube? (1) 25 (2) 100 (3) 50 (4) 5

Solution 14. (3) 1o/w/w w/N/N/N/N/N 4320 2160 1080 540 270 135 45 15 5 4320 = 2 x 2 x 2 x 2 x 2 x 3 x 3 x 3 x 5 Clearly, to make 4320 a perfect cube, it must be multiplied by 2 x 5 x 5 i.e. 50.