The CAS Registry Mumber 76128-92-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,6,1,2 and 8 respectively; the second part has 2 digits, 9 and 2 respectively. Calculate Digit Verification of CAS Registry Number 76128-92: (7*7)+(6*6)+(5*1)+(4*2)+(3*8)+(2*9)+(1*2)=142 142 % 10 = 2 So 76128-92-2 is a valid CAS Registry Number.