The CAS Registry Mumber 129878-49-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,9,8,7 and 8 respectively; the second part has 2 digits, 4 and 9 respectively. Calculate Digit Verification of CAS Registry Number 129878-49: (8*1)+(7*2)+(6*9)+(5*8)+(4*7)+(3*8)+(2*4)+(1*9)=185 185 % 10 = 5 So 129878-49-5 is a valid CAS Registry Number.