The CAS Registry Mumber 71475-87-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,1,4,7 and 5 respectively; the second part has 2 digits, 8 and 7 respectively. Calculate Digit Verification of CAS Registry Number 71475-87: (7*7)+(6*1)+(5*4)+(4*7)+(3*5)+(2*8)+(1*7)=141 141 % 10 = 1 So 71475-87-1 is a valid CAS Registry Number.