The CAS Registry Mumber 103751-19-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,3,7,5 and 1 respectively; the second part has 2 digits, 1 and 9 respectively. Calculate Digit Verification of CAS Registry Number 103751-19: (8*1)+(7*0)+(6*3)+(5*7)+(4*5)+(3*1)+(2*1)+(1*9)=95 95 % 10 = 5 So 103751-19-5 is a valid CAS Registry Number.