The CAS Registry Mumber 36881-68-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 3,6,8,8 and 1 respectively; the second part has 2 digits, 6 and 8 respectively. Calculate Digit Verification of CAS Registry Number 36881-68: (7*3)+(6*6)+(5*8)+(4*8)+(3*1)+(2*6)+(1*8)=152 152 % 10 = 2 So 36881-68-2 is a valid CAS Registry Number.