The CAS Registry Mumber 63017-26-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,3,0,1 and 7 respectively; the second part has 2 digits, 2 and 6 respectively. Calculate Digit Verification of CAS Registry Number 63017-26: (7*6)+(6*3)+(5*0)+(4*1)+(3*7)+(2*2)+(1*6)=95 95 % 10 = 5 So 63017-26-5 is a valid CAS Registry Number.