The CAS Registry Mumber 17264-03-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,7,2,6 and 4 respectively; the second part has 2 digits, 0 and 3 respectively. Calculate Digit Verification of CAS Registry Number 17264-03: (7*1)+(6*7)+(5*2)+(4*6)+(3*4)+(2*0)+(1*3)=98 98 % 10 = 8 So 17264-03-8 is a valid CAS Registry Number.