The CAS Registry Mumber 3205-46-7 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 3,2,0 and 5 respectively; the second part has 2 digits, 4 and 6 respectively. Calculate Digit Verification of CAS Registry Number 3205-46: (6*3)+(5*2)+(4*0)+(3*5)+(2*4)+(1*6)=57 57 % 10 = 7 So 3205-46-7 is a valid CAS Registry Number.