The CAS Registry Mumber 137628-29-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,7,6,2 and 8 respectively; the second part has 2 digits, 2 and 9 respectively. Calculate Digit Verification of CAS Registry Number 137628-29: (8*1)+(7*3)+(6*7)+(5*6)+(4*2)+(3*8)+(2*2)+(1*9)=146 146 % 10 = 6 So 137628-29-6 is a valid CAS Registry Number.