The CAS Registry Mumber 134176-57-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,4,1,7 and 6 respectively; the second part has 2 digits, 5 and 7 respectively. Calculate Digit Verification of CAS Registry Number 134176-57: (8*1)+(7*3)+(6*4)+(5*1)+(4*7)+(3*6)+(2*5)+(1*7)=121 121 % 10 = 1 So 134176-57-1 is a valid CAS Registry Number.