The CAS Registry Mumber 16910-19-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,6,9,1 and 0 respectively; the second part has 2 digits, 1 and 9 respectively. Calculate Digit Verification of CAS Registry Number 16910-19: (7*1)+(6*6)+(5*9)+(4*1)+(3*0)+(2*1)+(1*9)=103 103 % 10 = 3 So 16910-19-3 is a valid CAS Registry Number.