The CAS Registry Mumber 67428-47-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,7,4,2 and 8 respectively; the second part has 2 digits, 4 and 7 respectively. Calculate Digit Verification of CAS Registry Number 67428-47: (7*6)+(6*7)+(5*4)+(4*2)+(3*8)+(2*4)+(1*7)=151 151 % 10 = 1 So 67428-47-1 is a valid CAS Registry Number.