The CAS Registry Mumber 197-45-5 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 1,9 and 7 respectively; the second part has 2 digits, 4 and 5 respectively. Calculate Digit Verification of CAS Registry Number 197-45: (5*1)+(4*9)+(3*7)+(2*4)+(1*5)=75 75 % 10 = 5 So 197-45-5 is a valid CAS Registry Number.