The CAS Registry Mumber 77602-97-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,7,6,0 and 2 respectively; the second part has 2 digits, 9 and 7 respectively. Calculate Digit Verification of CAS Registry Number 77602-97: (7*7)+(6*7)+(5*6)+(4*0)+(3*2)+(2*9)+(1*7)=152 152 % 10 = 2 So 77602-97-2 is a valid CAS Registry Number.