The CAS Registry Mumber 98911-45-6 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 5 respectively. Calculate Digit Verification of CAS Registry Number 98911-45: (7*9)+(6*8)+(5*9)+(4*1)+(3*1)+(2*4)+(1*5)=176 176 % 10 = 6 So 98911-45-6 is a valid CAS Registry Number.