The CAS Registry Mumber 85434-18-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,5,4,3 and 4 respectively; the second part has 2 digits, 1 and 8 respectively. Calculate Digit Verification of CAS Registry Number 85434-18: (7*8)+(6*5)+(5*4)+(4*3)+(3*4)+(2*1)+(1*8)=140 140 % 10 = 0 So 85434-18-0 is a valid CAS Registry Number.