The CAS Registry Mumber 55865-75-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,5,8,6 and 5 respectively; the second part has 2 digits, 7 and 5 respectively. Calculate Digit Verification of CAS Registry Number 55865-75: (7*5)+(6*5)+(5*8)+(4*6)+(3*5)+(2*7)+(1*5)=163 163 % 10 = 3 So 55865-75-3 is a valid CAS Registry Number.