The CAS Registry Mumber 118139-59-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,8,1,3 and 9 respectively; the second part has 2 digits, 5 and 9 respectively. Calculate Digit Verification of CAS Registry Number 118139-59: (8*1)+(7*1)+(6*8)+(5*1)+(4*3)+(3*9)+(2*5)+(1*9)=126 126 % 10 = 6 So 118139-59-6 is a valid CAS Registry Number.