The CAS Registry Mumber 64361-93-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,4,3,6 and 1 respectively; the second part has 2 digits, 9 and 3 respectively. Calculate Digit Verification of CAS Registry Number 64361-93: (7*6)+(6*4)+(5*3)+(4*6)+(3*1)+(2*9)+(1*3)=129 129 % 10 = 9 So 64361-93-9 is a valid CAS Registry Number.