The CAS Registry Mumber 4612-65-1 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,6,1 and 2 respectively; the second part has 2 digits, 6 and 5 respectively. Calculate Digit Verification of CAS Registry Number 4612-65: (6*4)+(5*6)+(4*1)+(3*2)+(2*6)+(1*5)=81 81 % 10 = 1 So 4612-65-1 is a valid CAS Registry Number.