The CAS Registry Mumber 98911-47-8 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 7 respectively. Calculate Digit Verification of CAS Registry Number 98911-47: (7*9)+(6*8)+(5*9)+(4*1)+(3*1)+(2*4)+(1*7)=178 178 % 10 = 8 So 98911-47-8 is a valid CAS Registry Number.