The CAS Registry Mumber 188047-97-4 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,8,8,0,4 and 7 respectively; the second part has 2 digits, 9 and 7 respectively. Calculate Digit Verification of CAS Registry Number 188047-97: (8*1)+(7*8)+(6*8)+(5*0)+(4*4)+(3*7)+(2*9)+(1*7)=174 174 % 10 = 4 So 188047-97-4 is a valid CAS Registry Number.