The CAS Registry Mumber 94171-12-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,4,1,7 and 1 respectively; the second part has 2 digits, 1 and 2 respectively. Calculate Digit Verification of CAS Registry Number 94171-12: (7*9)+(6*4)+(5*1)+(4*7)+(3*1)+(2*1)+(1*2)=127 127 % 10 = 7 So 94171-12-7 is a valid CAS Registry Number.