The CAS Registry Mumber 89929-33-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,9,9,2 and 9 respectively; the second part has 2 digits, 3 and 3 respectively. Calculate Digit Verification of CAS Registry Number 89929-33: (7*8)+(6*9)+(5*9)+(4*2)+(3*9)+(2*3)+(1*3)=199 199 % 10 = 9 So 89929-33-9 is a valid CAS Registry Number.