The CAS Registry Mumber 9033-44-7 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 9,0,3 and 3 respectively; the second part has 2 digits, 4 and 4 respectively. Calculate Digit Verification of CAS Registry Number 9033-44: (6*9)+(5*0)+(4*3)+(3*3)+(2*4)+(1*4)=87 87 % 10 = 7 So 9033-44-7 is a valid CAS Registry Number.