The CAS Registry Mumber 67517-29-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,7,5,1 and 7 respectively; the second part has 2 digits, 2 and 9 respectively. Calculate Digit Verification of CAS Registry Number 67517-29: (7*6)+(6*7)+(5*5)+(4*1)+(3*7)+(2*2)+(1*9)=147 147 % 10 = 7 So 67517-29-7 is a valid CAS Registry Number.