The CAS Registry Mumber 106913-72-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,6,9,1 and 3 respectively; the second part has 2 digits, 7 and 2 respectively. Calculate Digit Verification of CAS Registry Number 106913-72: (8*1)+(7*0)+(6*6)+(5*9)+(4*1)+(3*3)+(2*7)+(1*2)=118 118 % 10 = 8 So 106913-72-8 is a valid CAS Registry Number.