The CAS Registry Mumber 59103-17-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,9,1,0 and 3 respectively; the second part has 2 digits, 1 and 7 respectively. Calculate Digit Verification of CAS Registry Number 59103-17: (7*5)+(6*9)+(5*1)+(4*0)+(3*3)+(2*1)+(1*7)=112 112 % 10 = 2 So 59103-17-2 is a valid CAS Registry Number.