The CAS Registry Mumber 79984-67-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,9,9,8 and 4 respectively; the second part has 2 digits, 6 and 7 respectively. Calculate Digit Verification of CAS Registry Number 79984-67: (7*7)+(6*9)+(5*9)+(4*8)+(3*4)+(2*6)+(1*7)=211 211 % 10 = 1 So 79984-67-1 is a valid CAS Registry Number.