Find the common denominator of: 1^1/12 + 2^3/18 + 3^3/36

12  =  3 * 2^2

18  = 3^2 * 2

36 =  3^2 * 2^2

Taking the greatest   powers on 2 and 3 that appear, we  have

3^2 * 2^2  =  36   = the common denominator.....!!!