The CAS Registry Mumber 1262538-11-3 includes 10 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 7 digits, 1,2,6,2,5,3 and 8 respectively; the second part has 2 digits, 1 and 1 respectively. Calculate Digit Verification of CAS Registry Number 1262538-11: (9*1)+(8*2)+(7*6)+(6*2)+(5*5)+(4*3)+(3*8)+(2*1)+(1*1)=143 143 % 10 = 3 So 1262538-11-3 is a valid CAS Registry Number.