The CAS Registry Mumber 259880-39-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 2,5,9,8,8 and 0 respectively; the second part has 2 digits, 3 and 9 respectively. Calculate Digit Verification of CAS Registry Number 259880-39: (8*2)+(7*5)+(6*9)+(5*8)+(4*8)+(3*0)+(2*3)+(1*9)=192 192 % 10 = 2 So 259880-39-2 is a valid CAS Registry Number.