The CAS Registry Mumber 229010-20-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 2,2,9,0,1 and 0 respectively; the second part has 2 digits, 2 and 0 respectively. Calculate Digit Verification of CAS Registry Number 229010-20: (8*2)+(7*2)+(6*9)+(5*0)+(4*1)+(3*0)+(2*2)+(1*0)=92 92 % 10 = 2 So 229010-20-2 is a valid CAS Registry Number.