The minimum soldiers that can be arranged in 8, 12, 16 and 20 rows of equal soldiers and also arrange them in a square format will be:

3600

Minimum soldiers = LCM of 8, 12, 16, 20 = 240

** The minimum number is 240 but its square root is not a whole number. Therefore, we need a number which is multiple of 240 and a perfect square of a whole number also.

Hence, the minimum no. = 240 × 15 = 3600.