The CAS Registry Mumber 40103-72-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 4,0,1,0 and 3 respectively; the second part has 2 digits, 7 and 2 respectively. Calculate Digit Verification of CAS Registry Number 40103-72: (7*4)+(6*0)+(5*1)+(4*0)+(3*3)+(2*7)+(1*2)=58 58 % 10 = 8 So 40103-72-8 is a valid CAS Registry Number.