The CAS Registry Mumber 108173-48-4 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,8,1,7 and 3 respectively; the second part has 2 digits, 4 and 8 respectively. Calculate Digit Verification of CAS Registry Number 108173-48: (8*1)+(7*0)+(6*8)+(5*1)+(4*7)+(3*3)+(2*4)+(1*8)=114 114 % 10 = 4 So 108173-48-4 is a valid CAS Registry Number.