The CAS Registry Mumber 1302-72-3 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 1,3,0 and 2 respectively; the second part has 2 digits, 7 and 2 respectively. Calculate Digit Verification of CAS Registry Number 1302-72: (6*1)+(5*3)+(4*0)+(3*2)+(2*7)+(1*2)=43 43 % 10 = 3 So 1302-72-3 is a valid CAS Registry Number.