The CAS Registry Mumber 75759-74-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,5,7,5 and 9 respectively; the second part has 2 digits, 7 and 4 respectively. Calculate Digit Verification of CAS Registry Number 75759-74: (7*7)+(6*5)+(5*7)+(4*5)+(3*9)+(2*7)+(1*4)=179 179 % 10 = 9 So 75759-74-9 is a valid CAS Registry Number.