The CAS Registry Mumber 40600-20-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 4,0,6,0 and 0 respectively; the second part has 2 digits, 2 and 0 respectively. Calculate Digit Verification of CAS Registry Number 40600-20: (7*4)+(6*0)+(5*6)+(4*0)+(3*0)+(2*2)+(1*0)=62 62 % 10 = 2 So 40600-20-2 is a valid CAS Registry Number.