The CAS Registry Mumber 96983-75-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,6,9,8 and 3 respectively; the second part has 2 digits, 7 and 5 respectively. Calculate Digit Verification of CAS Registry Number 96983-75: (7*9)+(6*6)+(5*9)+(4*8)+(3*3)+(2*7)+(1*5)=204 204 % 10 = 4 So 96983-75-4 is a valid CAS Registry Number.