The CAS Registry Mumber 64728-92-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,4,7,2 and 8 respectively; the second part has 2 digits, 9 and 2 respectively. Calculate Digit Verification of CAS Registry Number 64728-92: (7*6)+(6*4)+(5*7)+(4*2)+(3*8)+(2*9)+(1*2)=153 153 % 10 = 3 So 64728-92-3 is a valid CAS Registry Number.