The CAS Registry Mumber 4507-97-5 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,5,0 and 7 respectively; the second part has 2 digits, 9 and 7 respectively. Calculate Digit Verification of CAS Registry Number 4507-97: (6*4)+(5*5)+(4*0)+(3*7)+(2*9)+(1*7)=95 95 % 10 = 5 So 4507-97-5 is a valid CAS Registry Number.