The CAS Registry Mumber 87281-92-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,7,2,8 and 1 respectively; the second part has 2 digits, 9 and 2 respectively. Calculate Digit Verification of CAS Registry Number 87281-92: (7*8)+(6*7)+(5*2)+(4*8)+(3*1)+(2*9)+(1*2)=163 163 % 10 = 3 So 87281-92-3 is a valid CAS Registry Number.