The CAS Registry Mumber 1026704-79-9 includes 10 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 7 digits, 1,0,2,6,7,0 and 4 respectively; the second part has 2 digits, 7 and 9 respectively. Calculate Digit Verification of CAS Registry Number 1026704-79: (9*1)+(8*0)+(7*2)+(6*6)+(5*7)+(4*0)+(3*4)+(2*7)+(1*9)=129 129 % 10 = 9 So 1026704-79-9 is a valid CAS Registry Number.