The CAS Registry Mumber 33407-62-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 3,3,4,0 and 7 respectively; the second part has 2 digits, 6 and 2 respectively. Calculate Digit Verification of CAS Registry Number 33407-62: (7*3)+(6*3)+(5*4)+(4*0)+(3*7)+(2*6)+(1*2)=94 94 % 10 = 4 So 33407-62-4 is a valid CAS Registry Number.