The CAS Registry Mumber 72867-16-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,2,8,6 and 7 respectively; the second part has 2 digits, 1 and 6 respectively. Calculate Digit Verification of CAS Registry Number 72867-16: (7*7)+(6*2)+(5*8)+(4*6)+(3*7)+(2*1)+(1*6)=154 154 % 10 = 4 So 72867-16-4 is a valid CAS Registry Number.