The CAS Registry Mumber 103088-30-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,3,0,8 and 8 respectively; the second part has 2 digits, 3 and 0 respectively. Calculate Digit Verification of CAS Registry Number 103088-30: (8*1)+(7*0)+(6*3)+(5*0)+(4*8)+(3*8)+(2*3)+(1*0)=88 88 % 10 = 8 So 103088-30-8 is a valid CAS Registry Number.