The CAS Registry Mumber 8025-63-6 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 8,0,2 and 5 respectively; the second part has 2 digits, 6 and 3 respectively. Calculate Digit Verification of CAS Registry Number 8025-63: (6*8)+(5*0)+(4*2)+(3*5)+(2*6)+(1*3)=86 86 % 10 = 6 So 8025-63-6 is a valid CAS Registry Number.