The CAS Registry Mumber 77397-49-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,7,3,9 and 7 respectively; the second part has 2 digits, 4 and 9 respectively. Calculate Digit Verification of CAS Registry Number 77397-49: (7*7)+(6*7)+(5*3)+(4*9)+(3*7)+(2*4)+(1*9)=180 180 % 10 = 0 So 77397-49-0 is a valid CAS Registry Number.