The CAS Registry Mumber 76663-00-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,6,6,6 and 3 respectively; the second part has 2 digits, 0 and 0 respectively. Calculate Digit Verification of CAS Registry Number 76663-00: (7*7)+(6*6)+(5*6)+(4*6)+(3*3)+(2*0)+(1*0)=148 148 % 10 = 8 So 76663-00-8 is a valid CAS Registry Number.