The CAS Registry Mumber 329309-57-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 3,2,9,3,0 and 9 respectively; the second part has 2 digits, 5 and 7 respectively. Calculate Digit Verification of CAS Registry Number 329309-57: (8*3)+(7*2)+(6*9)+(5*3)+(4*0)+(3*9)+(2*5)+(1*7)=151 151 % 10 = 1 So 329309-57-1 is a valid CAS Registry Number.