The CAS Registry Mumber 17795-68-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,7,7,9 and 5 respectively; the second part has 2 digits, 6 and 8 respectively. Calculate Digit Verification of CAS Registry Number 17795-68: (7*1)+(6*7)+(5*7)+(4*9)+(3*5)+(2*6)+(1*8)=155 155 % 10 = 5 So 17795-68-5 is a valid CAS Registry Number.