The CAS Registry Mumber 61929-18-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,1,9,2 and 9 respectively; the second part has 2 digits, 1 and 8 respectively. Calculate Digit Verification of CAS Registry Number 61929-18: (7*6)+(6*1)+(5*9)+(4*2)+(3*9)+(2*1)+(1*8)=138 138 % 10 = 8 So 61929-18-8 is a valid CAS Registry Number.