The CAS Registry Mumber 113696-51-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,3,6,9 and 6 respectively; the second part has 2 digits, 5 and 1 respectively. Calculate Digit Verification of CAS Registry Number 113696-51: (8*1)+(7*1)+(6*3)+(5*6)+(4*9)+(3*6)+(2*5)+(1*1)=128 128 % 10 = 8 So 113696-51-8 is a valid CAS Registry Number.