The CAS Registry Mumber 34655-69-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 3,4,6,5 and 5 respectively; the second part has 2 digits, 6 and 9 respectively. Calculate Digit Verification of CAS Registry Number 34655-69: (7*3)+(6*4)+(5*6)+(4*5)+(3*5)+(2*6)+(1*9)=131 131 % 10 = 1 So 34655-69-1 is a valid CAS Registry Number.