The CAS Registry Mumber 13861-19-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,3,8,6 and 1 respectively; the second part has 2 digits, 1 and 9 respectively. Calculate Digit Verification of CAS Registry Number 13861-19: (7*1)+(6*3)+(5*8)+(4*6)+(3*1)+(2*1)+(1*9)=103 103 % 10 = 3 So 13861-19-3 is a valid CAS Registry Number.