The CAS Registry Mumber 927887-18-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 9,2,7,8,8 and 7 respectively; the second part has 2 digits, 1 and 8 respectively. Calculate Digit Verification of CAS Registry Number 927887-18: (8*9)+(7*2)+(6*7)+(5*8)+(4*8)+(3*7)+(2*1)+(1*8)=231 231 % 10 = 1 So 927887-18-1 is a valid CAS Registry Number.