The CAS Registry Mumber 68917-32-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,8,9,1 and 7 respectively; the second part has 2 digits, 3 and 2 respectively. Calculate Digit Verification of CAS Registry Number 68917-32: (7*6)+(6*8)+(5*9)+(4*1)+(3*7)+(2*3)+(1*2)=168 168 % 10 = 8 So 68917-32-8 is a valid CAS Registry Number.