The CAS Registry Mumber 86611-30-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,6,6,1 and 1 respectively; the second part has 2 digits, 3 and 0 respectively. Calculate Digit Verification of CAS Registry Number 86611-30: (7*8)+(6*6)+(5*6)+(4*1)+(3*1)+(2*3)+(1*0)=135 135 % 10 = 5 So 86611-30-5 is a valid CAS Registry Number.