The CAS Registry Mumber 139452-26-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,9,4,5 and 2 respectively; the second part has 2 digits, 2 and 6 respectively. Calculate Digit Verification of CAS Registry Number 139452-26: (8*1)+(7*3)+(6*9)+(5*4)+(4*5)+(3*2)+(2*2)+(1*6)=139 139 % 10 = 9 So 139452-26-9 is a valid CAS Registry Number.