The CAS Registry Mumber 37268-38-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 3,7,2,6 and 8 respectively; the second part has 2 digits, 3 and 8 respectively. Calculate Digit Verification of CAS Registry Number 37268-38: (7*3)+(6*7)+(5*2)+(4*6)+(3*8)+(2*3)+(1*8)=135 135 % 10 = 5 So 37268-38-5 is a valid CAS Registry Number.