The CAS Registry Mumber 4017-07-6 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,0,1 and 7 respectively; the second part has 2 digits, 0 and 7 respectively. Calculate Digit Verification of CAS Registry Number 4017-07: (6*4)+(5*0)+(4*1)+(3*7)+(2*0)+(1*7)=56 56 % 10 = 6 So 4017-07-6 is a valid CAS Registry Number.