The CAS Registry Mumber 27963-88-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 2,7,9,6 and 3 respectively; the second part has 2 digits, 8 and 8 respectively. Calculate Digit Verification of CAS Registry Number 27963-88: (7*2)+(6*7)+(5*9)+(4*6)+(3*3)+(2*8)+(1*8)=158 158 % 10 = 8 So 27963-88-8 is a valid CAS Registry Number.