The CAS Registry Mumber 71868-47-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,1,8,6 and 8 respectively; the second part has 2 digits, 4 and 7 respectively. Calculate Digit Verification of CAS Registry Number 71868-47: (7*7)+(6*1)+(5*8)+(4*6)+(3*8)+(2*4)+(1*7)=158 158 % 10 = 8 So 71868-47-8 is a valid CAS Registry Number.