The CAS Registry Mumber 3946-61-0 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 3,9,4 and 6 respectively; the second part has 2 digits, 6 and 1 respectively. Calculate Digit Verification of CAS Registry Number 3946-61: (6*3)+(5*9)+(4*4)+(3*6)+(2*6)+(1*1)=110 110 % 10 = 0 So 3946-61-0 is a valid CAS Registry Number.