The CAS Registry Mumber 210830-69-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 2,1,0,8,3 and 0 respectively; the second part has 2 digits, 6 and 9 respectively. Calculate Digit Verification of CAS Registry Number 210830-69: (8*2)+(7*1)+(6*0)+(5*8)+(4*3)+(3*0)+(2*6)+(1*9)=96 96 % 10 = 6 So 210830-69-6 is a valid CAS Registry Number.