The CAS Registry Mumber 63205-34-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,3,2,0 and 5 respectively; the second part has 2 digits, 3 and 4 respectively. Calculate Digit Verification of CAS Registry Number 63205-34: (7*6)+(6*3)+(5*2)+(4*0)+(3*5)+(2*3)+(1*4)=95 95 % 10 = 5 So 63205-34-5 is a valid CAS Registry Number.