The CAS Registry Mumber 1263184-89-9 includes 10 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 7 digits, 1,2,6,3,1,8 and 4 respectively; the second part has 2 digits, 8 and 9 respectively. Calculate Digit Verification of CAS Registry Number 1263184-89: (9*1)+(8*2)+(7*6)+(6*3)+(5*1)+(4*8)+(3*4)+(2*8)+(1*9)=159 159 % 10 = 9 So 1263184-89-9 is a valid CAS Registry Number.