The CAS Registry Mumber 64385-16-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,4,3,8 and 5 respectively; the second part has 2 digits, 1 and 6 respectively. Calculate Digit Verification of CAS Registry Number 64385-16: (7*6)+(6*4)+(5*3)+(4*8)+(3*5)+(2*1)+(1*6)=136 136 % 10 = 6 So 64385-16-6 is a valid CAS Registry Number.