The CAS Registry Mumber 76984-98-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,6,9,8 and 4 respectively; the second part has 2 digits, 9 and 8 respectively. Calculate Digit Verification of CAS Registry Number 76984-98: (7*7)+(6*6)+(5*9)+(4*8)+(3*4)+(2*9)+(1*8)=200 200 % 10 = 0 So 76984-98-0 is a valid CAS Registry Number.