The CAS Registry Mumber 98911-44-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,8,9,1 and 1 respectively; the second part has 2 digits, 4 and 4 respectively. Calculate Digit Verification of CAS Registry Number 98911-44: (7*9)+(6*8)+(5*9)+(4*1)+(3*1)+(2*4)+(1*4)=175 175 % 10 = 5 So 98911-44-5 is a valid CAS Registry Number.