The CAS Registry Mumber 5304-92-7 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 5,3,0 and 4 respectively; the second part has 2 digits, 9 and 2 respectively. Calculate Digit Verification of CAS Registry Number 5304-92: (6*5)+(5*3)+(4*0)+(3*4)+(2*9)+(1*2)=77 77 % 10 = 7 So 5304-92-7 is a valid CAS Registry Number.