The CAS Registry Mumber 187-96-2 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 1,8 and 7 respectively; the second part has 2 digits, 9 and 6 respectively. Calculate Digit Verification of CAS Registry Number 187-96: (5*1)+(4*8)+(3*7)+(2*9)+(1*6)=82 82 % 10 = 2 So 187-96-2 is a valid CAS Registry Number.