The CAS Registry Mumber 1806-12-8 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 1,8,0 and 6 respectively; the second part has 2 digits, 1 and 2 respectively. Calculate Digit Verification of CAS Registry Number 1806-12: (6*1)+(5*8)+(4*0)+(3*6)+(2*1)+(1*2)=68 68 % 10 = 8 So 1806-12-8 is a valid CAS Registry Number.