The CAS Registry Mumber 77335-73-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,7,3,3 and 5 respectively; the second part has 2 digits, 7 and 3 respectively. Calculate Digit Verification of CAS Registry Number 77335-73: (7*7)+(6*7)+(5*3)+(4*3)+(3*5)+(2*7)+(1*3)=150 150 % 10 = 0 So 77335-73-0 is a valid CAS Registry Number.