The CAS Registry Mumber 568-99-0 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 5,6 and 8 respectively; the second part has 2 digits, 9 and 9 respectively. Calculate Digit Verification of CAS Registry Number 568-99: (5*5)+(4*6)+(3*8)+(2*9)+(1*9)=100 100 % 10 = 0 So 568-99-0 is a valid CAS Registry Number.