The CAS Registry Mumber 63830-56-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,3,8,3 and 0 respectively; the second part has 2 digits, 5 and 6 respectively. Calculate Digit Verification of CAS Registry Number 63830-56: (7*6)+(6*3)+(5*8)+(4*3)+(3*0)+(2*5)+(1*6)=128 128 % 10 = 8 So 63830-56-8 is a valid CAS Registry Number.