The CAS Registry Mumber 110259-09-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,0,2,5 and 9 respectively; the second part has 2 digits, 0 and 9 respectively. Calculate Digit Verification of CAS Registry Number 110259-09: (8*1)+(7*1)+(6*0)+(5*2)+(4*5)+(3*9)+(2*0)+(1*9)=81 81 % 10 = 1 So 110259-09-1 is a valid CAS Registry Number.