The CAS Registry Mumber 18330-27-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,8,3,3 and 0 respectively; the second part has 2 digits, 2 and 7 respectively. Calculate Digit Verification of CAS Registry Number 18330-27: (7*1)+(6*8)+(5*3)+(4*3)+(3*0)+(2*2)+(1*7)=93 93 % 10 = 3 So 18330-27-3 is a valid CAS Registry Number.