The CAS Registry Mumber 126904-29-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,6,9,0 and 4 respectively; the second part has 2 digits, 2 and 9 respectively. Calculate Digit Verification of CAS Registry Number 126904-29: (8*1)+(7*2)+(6*6)+(5*9)+(4*0)+(3*4)+(2*2)+(1*9)=128 128 % 10 = 8 So 126904-29-8 is a valid CAS Registry Number.