The CAS Registry Mumber 86759-05-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,6,7,5 and 9 respectively; the second part has 2 digits, 0 and 5 respectively. Calculate Digit Verification of CAS Registry Number 86759-05: (7*8)+(6*6)+(5*7)+(4*5)+(3*9)+(2*0)+(1*5)=179 179 % 10 = 9 So 86759-05-9 is a valid CAS Registry Number.