The CAS Registry Mumber 74757-94-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,4,7,5 and 7 respectively; the second part has 2 digits, 9 and 4 respectively. Calculate Digit Verification of CAS Registry Number 74757-94: (7*7)+(6*4)+(5*7)+(4*5)+(3*7)+(2*9)+(1*4)=171 171 % 10 = 1 So 74757-94-1 is a valid CAS Registry Number.