The CAS Registry Mumber 13002-87-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,3,0,0 and 2 respectively; the second part has 2 digits, 8 and 7 respectively. Calculate Digit Verification of CAS Registry Number 13002-87: (7*1)+(6*3)+(5*0)+(4*0)+(3*2)+(2*8)+(1*7)=54 54 % 10 = 4 So 13002-87-4 is a valid CAS Registry Number.