The CAS Registry Mumber 85090-30-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,5,0,9 and 0 respectively; the second part has 2 digits, 3 and 0 respectively. Calculate Digit Verification of CAS Registry Number 85090-30: (7*8)+(6*5)+(5*0)+(4*9)+(3*0)+(2*3)+(1*0)=128 128 % 10 = 8 So 85090-30-8 is a valid CAS Registry Number.