Quant Boosters  Hemant Malhotra  Set 9

Method 1 
Product of factors = N (number of factors/2))
let 6th factor = k
so k * 648 = N^3
so k * 3^4 * 2^3 = N^3
RHS is prefect cube so LHS shuld be perfect cube
so k = 3^2 = 9Method2 : N = 2 * 3^2
648 = 1 * 2 * 3 * 6 * 18
remaining 9 so OA = 9

@hemant_malhotra I don't understand how 248 came