The CAS Registry Mumber 65054-17-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,5,0,5 and 4 respectively; the second part has 2 digits, 1 and 7 respectively. Calculate Digit Verification of CAS Registry Number 65054-17: (7*6)+(6*5)+(5*0)+(4*5)+(3*4)+(2*1)+(1*7)=113 113 % 10 = 3 So 65054-17-3 is a valid CAS Registry Number.