The CAS Registry Mumber 3814-11-7 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 4 respectively; the second part has 2 digits, 1 and 1 respectively. Calculate Digit Verification of CAS Registry Number 3814-11: (6*3)+(5*8)+(4*1)+(3*4)+(2*1)+(1*1)=77 77 % 10 = 7 So 3814-11-7 is a valid CAS Registry Number.