The CAS Registry Mumber 1337881-43-2 includes 10 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 7 digits, 1,3,3,7,8,8 and 1 respectively; the second part has 2 digits, 4 and 3 respectively. Calculate Digit Verification of CAS Registry Number 1337881-43: (9*1)+(8*3)+(7*3)+(6*7)+(5*8)+(4*8)+(3*1)+(2*4)+(1*3)=182 182 % 10 = 2 So 1337881-43-2 is a valid CAS Registry Number.