The CAS Registry Mumber 18200-01-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,8,2,0 and 0 respectively; the second part has 2 digits, 0 and 1 respectively. Calculate Digit Verification of CAS Registry Number 18200-01: (7*1)+(6*8)+(5*2)+(4*0)+(3*0)+(2*0)+(1*1)=66 66 % 10 = 6 So 18200-01-6 is a valid CAS Registry Number.