The CAS Registry Mumber 2867-51-8 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 2,8,6 and 7 respectively; the second part has 2 digits, 5 and 1 respectively. Calculate Digit Verification of CAS Registry Number 2867-51: (6*2)+(5*8)+(4*6)+(3*7)+(2*5)+(1*1)=108 108 % 10 = 8 So 2867-51-8 is a valid CAS Registry Number.