The CAS Registry Mumber 81540-47-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,1,5,4 and 0 respectively; the second part has 2 digits, 4 and 7 respectively. Calculate Digit Verification of CAS Registry Number 81540-47: (7*8)+(6*1)+(5*5)+(4*4)+(3*0)+(2*4)+(1*7)=118 118 % 10 = 8 So 81540-47-8 is a valid CAS Registry Number.