The CAS Registry Mumber 67341-93-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,7,3,4 and 1 respectively; the second part has 2 digits, 9 and 3 respectively. Calculate Digit Verification of CAS Registry Number 67341-93: (7*6)+(6*7)+(5*3)+(4*4)+(3*1)+(2*9)+(1*3)=139 139 % 10 = 9 So 67341-93-9 is a valid CAS Registry Number.