The CAS Registry Mumber 118973-58-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,8,9,7 and 3 respectively; the second part has 2 digits, 5 and 8 respectively. Calculate Digit Verification of CAS Registry Number 118973-58: (8*1)+(7*1)+(6*8)+(5*9)+(4*7)+(3*3)+(2*5)+(1*8)=163 163 % 10 = 3 So 118973-58-3 is a valid CAS Registry Number.