The CAS Registry Mumber 790998-75-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 7,9,0,9,9 and 8 respectively; the second part has 2 digits, 7 and 5 respectively. Calculate Digit Verification of CAS Registry Number 790998-75: (8*7)+(7*9)+(6*0)+(5*9)+(4*9)+(3*8)+(2*7)+(1*5)=243 243 % 10 = 3 So 790998-75-3 is a valid CAS Registry Number.