The CAS Registry Mumber 74857-07-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,4,8,5 and 7 respectively; the second part has 2 digits, 0 and 7 respectively. Calculate Digit Verification of CAS Registry Number 74857-07: (7*7)+(6*4)+(5*8)+(4*5)+(3*7)+(2*0)+(1*7)=161 161 % 10 = 1 So 74857-07-1 is a valid CAS Registry Number.