The CAS Registry Mumber 72302-98-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,2,3,0 and 2 respectively; the second part has 2 digits, 9 and 8 respectively. Calculate Digit Verification of CAS Registry Number 72302-98: (7*7)+(6*2)+(5*3)+(4*0)+(3*2)+(2*9)+(1*8)=108 108 % 10 = 8 So 72302-98-8 is a valid CAS Registry Number.