The CAS Registry Mumber 129279-84-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,9,2,7 and 9 respectively; the second part has 2 digits, 8 and 4 respectively. Calculate Digit Verification of CAS Registry Number 129279-84: (8*1)+(7*2)+(6*9)+(5*2)+(4*7)+(3*9)+(2*8)+(1*4)=161 161 % 10 = 1 So 129279-84-1 is a valid CAS Registry Number.