The CAS Registry Mumber 39603-90-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 3,9,6,0 and 3 respectively; the second part has 2 digits, 9 and 0 respectively. Calculate Digit Verification of CAS Registry Number 39603-90: (7*3)+(6*9)+(5*6)+(4*0)+(3*3)+(2*9)+(1*0)=132 132 % 10 = 2 So 39603-90-2 is a valid CAS Registry Number.