The CAS Registry Mumber 58611-87-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,8,6,1 and 1 respectively; the second part has 2 digits, 8 and 7 respectively. Calculate Digit Verification of CAS Registry Number 58611-87: (7*5)+(6*8)+(5*6)+(4*1)+(3*1)+(2*8)+(1*7)=143 143 % 10 = 3 So 58611-87-3 is a valid CAS Registry Number.