The CAS Registry Mumber 90106-33-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,0,1,0 and 6 respectively; the second part has 2 digits, 3 and 3 respectively. Calculate Digit Verification of CAS Registry Number 90106-33: (7*9)+(6*0)+(5*1)+(4*0)+(3*6)+(2*3)+(1*3)=95 95 % 10 = 5 So 90106-33-5 is a valid CAS Registry Number.