The CAS Registry Mumber 75910-98-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,5,9,1 and 0 respectively; the second part has 2 digits, 9 and 8 respectively. Calculate Digit Verification of CAS Registry Number 75910-98: (7*7)+(6*5)+(5*9)+(4*1)+(3*0)+(2*9)+(1*8)=154 154 % 10 = 4 So 75910-98-4 is a valid CAS Registry Number.