The CAS Registry Mumber 386218-09-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 3,8,6,2,1 and 8 respectively; the second part has 2 digits, 0 and 9 respectively. Calculate Digit Verification of CAS Registry Number 386218-09: (8*3)+(7*8)+(6*6)+(5*2)+(4*1)+(3*8)+(2*0)+(1*9)=163 163 % 10 = 3 So 386218-09-3 is a valid CAS Registry Number.