The CAS Registry Mumber 76629-55-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,6,6,2 and 9 respectively; the second part has 2 digits, 5 and 5 respectively. Calculate Digit Verification of CAS Registry Number 76629-55: (7*7)+(6*6)+(5*6)+(4*2)+(3*9)+(2*5)+(1*5)=165 165 % 10 = 5 So 76629-55-5 is a valid CAS Registry Number.