The CAS Registry Mumber 3819-63-4 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 3,8,1 and 9 respectively; the second part has 2 digits, 6 and 3 respectively. Calculate Digit Verification of CAS Registry Number 3819-63: (6*3)+(5*8)+(4*1)+(3*9)+(2*6)+(1*3)=104 104 % 10 = 4 So 3819-63-4 is a valid CAS Registry Number.