The CAS Registry Mumber 7112-17-6 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 7,1,1 and 2 respectively; the second part has 2 digits, 1 and 7 respectively. Calculate Digit Verification of CAS Registry Number 7112-17: (6*7)+(5*1)+(4*1)+(3*2)+(2*1)+(1*7)=66 66 % 10 = 6 So 7112-17-6 is a valid CAS Registry Number.