The CAS Registry Mumber 747398-65-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 7,4,7,3,9 and 8 respectively; the second part has 2 digits, 6 and 5 respectively. Calculate Digit Verification of CAS Registry Number 747398-65: (8*7)+(7*4)+(6*7)+(5*3)+(4*9)+(3*8)+(2*6)+(1*5)=218 218 % 10 = 8 So 747398-65-8 is a valid CAS Registry Number.