The CAS Registry Mumber 28583-76-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 2,8,5,8 and 3 respectively; the second part has 2 digits, 7 and 6 respectively. Calculate Digit Verification of CAS Registry Number 28583-76: (7*2)+(6*8)+(5*5)+(4*8)+(3*3)+(2*7)+(1*6)=148 148 % 10 = 8 So 28583-76-8 is a valid CAS Registry Number.