The CAS Registry Mumber 108141-81-7 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,8,1,4 and 1 respectively; the second part has 2 digits, 8 and 1 respectively. Calculate Digit Verification of CAS Registry Number 108141-81: (8*1)+(7*0)+(6*8)+(5*1)+(4*4)+(3*1)+(2*8)+(1*1)=97 97 % 10 = 7 So 108141-81-7 is a valid CAS Registry Number.