The CAS Registry Mumber 84379-59-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,4,3,7 and 9 respectively; the second part has 2 digits, 5 and 9 respectively. Calculate Digit Verification of CAS Registry Number 84379-59: (7*8)+(6*4)+(5*3)+(4*7)+(3*9)+(2*5)+(1*9)=169 169 % 10 = 9 So 84379-59-9 is a valid CAS Registry Number.