The CAS Registry Mumber 4871-02-7 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,8,7 and 1 respectively; the second part has 2 digits, 0 and 2 respectively. Calculate Digit Verification of CAS Registry Number 4871-02: (6*4)+(5*8)+(4*7)+(3*1)+(2*0)+(1*2)=97 97 % 10 = 7 So 4871-02-7 is a valid CAS Registry Number.