The CAS Registry Mumber 77711-07-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,7,7,1 and 1 respectively; the second part has 2 digits, 0 and 7 respectively. Calculate Digit Verification of CAS Registry Number 77711-07: (7*7)+(6*7)+(5*7)+(4*1)+(3*1)+(2*0)+(1*7)=140 140 % 10 = 0 So 77711-07-0 is a valid CAS Registry Number.