The CAS Registry Mumber 16601-10-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,6,6,0 and 1 respectively; the second part has 2 digits, 1 and 0 respectively. Calculate Digit Verification of CAS Registry Number 16601-10: (7*1)+(6*6)+(5*6)+(4*0)+(3*1)+(2*1)+(1*0)=78 78 % 10 = 8 So 16601-10-8 is a valid CAS Registry Number.