The CAS Registry Mumber 101353-93-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,1,3,5 and 3 respectively; the second part has 2 digits, 9 and 3 respectively. Calculate Digit Verification of CAS Registry Number 101353-93: (8*1)+(7*0)+(6*1)+(5*3)+(4*5)+(3*3)+(2*9)+(1*3)=79 79 % 10 = 9 So 101353-93-9 is a valid CAS Registry Number.