The CAS Registry Mumber 96631-27-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,6,6,3 and 1 respectively; the second part has 2 digits, 2 and 7 respectively. Calculate Digit Verification of CAS Registry Number 96631-27: (7*9)+(6*6)+(5*6)+(4*3)+(3*1)+(2*2)+(1*7)=155 155 % 10 = 5 So 96631-27-5 is a valid CAS Registry Number.