The CAS Registry Mumber 98982-81-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,8,9,8 and 2 respectively; the second part has 2 digits, 8 and 1 respectively. Calculate Digit Verification of CAS Registry Number 98982-81: (7*9)+(6*8)+(5*9)+(4*8)+(3*2)+(2*8)+(1*1)=211 211 % 10 = 1 So 98982-81-1 is a valid CAS Registry Number.