The CAS Registry Mumber 102634-19-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,2,6,3 and 4 respectively; the second part has 2 digits, 1 and 9 respectively. Calculate Digit Verification of CAS Registry Number 102634-19: (8*1)+(7*0)+(6*2)+(5*6)+(4*3)+(3*4)+(2*1)+(1*9)=85 85 % 10 = 5 So 102634-19-5 is a valid CAS Registry Number.