The CAS Registry Mumber 5185-79-5 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 5,1,8 and 5 respectively; the second part has 2 digits, 7 and 9 respectively. Calculate Digit Verification of CAS Registry Number 5185-79: (6*5)+(5*1)+(4*8)+(3*5)+(2*7)+(1*9)=105 105 % 10 = 5 So 5185-79-5 is a valid CAS Registry Number.