The CAS Registry Mumber 888615-87-0 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 8,8,8,6,1 and 5 respectively; the second part has 2 digits, 8 and 7 respectively. Calculate Digit Verification of CAS Registry Number 888615-87: (8*8)+(7*8)+(6*8)+(5*6)+(4*1)+(3*5)+(2*8)+(1*7)=240 240 % 10 = 0 So 888615-87-0 is a valid CAS Registry Number.