The CAS Registry Mumber 4043-74-7 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,0,4 and 3 respectively; the second part has 2 digits, 7 and 4 respectively. Calculate Digit Verification of CAS Registry Number 4043-74: (6*4)+(5*0)+(4*4)+(3*3)+(2*7)+(1*4)=67 67 % 10 = 7 So 4043-74-7 is a valid CAS Registry Number.