The CAS Registry Mumber 2899-00-5 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 2,8,9 and 9 respectively; the second part has 2 digits, 0 and 0 respectively. Calculate Digit Verification of CAS Registry Number 2899-00: (6*2)+(5*8)+(4*9)+(3*9)+(2*0)+(1*0)=115 115 % 10 = 5 So 2899-00-5 is a valid CAS Registry Number.