The CAS Registry Mumber 829-77-6 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 8,2 and 9 respectively; the second part has 2 digits, 7 and 7 respectively. Calculate Digit Verification of CAS Registry Number 829-77: (5*8)+(4*2)+(3*9)+(2*7)+(1*7)=96 96 % 10 = 6 So 829-77-6 is a valid CAS Registry Number.