The CAS Registry Mumber 8011-89-0 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 8,0,1 and 1 respectively; the second part has 2 digits, 8 and 9 respectively. Calculate Digit Verification of CAS Registry Number 8011-89: (6*8)+(5*0)+(4*1)+(3*1)+(2*8)+(1*9)=80 80 % 10 = 0 So 8011-89-0 is a valid CAS Registry Number.