The CAS Registry Mumber 75305-14-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,5,3,0 and 5 respectively; the second part has 2 digits, 1 and 4 respectively. Calculate Digit Verification of CAS Registry Number 75305-14: (7*7)+(6*5)+(5*3)+(4*0)+(3*5)+(2*1)+(1*4)=115 115 % 10 = 5 So 75305-14-5 is a valid CAS Registry Number.