The CAS Registry Mumber 4201-69-8 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,2,0 and 1 respectively; the second part has 2 digits, 6 and 9 respectively. Calculate Digit Verification of CAS Registry Number 4201-69: (6*4)+(5*2)+(4*0)+(3*1)+(2*6)+(1*9)=58 58 % 10 = 8 So 4201-69-8 is a valid CAS Registry Number.