The CAS Registry Mumber 2059-01-0 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 2,0,5 and 9 respectively; the second part has 2 digits, 0 and 1 respectively. Calculate Digit Verification of CAS Registry Number 2059-01: (6*2)+(5*0)+(4*5)+(3*9)+(2*0)+(1*1)=60 60 % 10 = 0 So 2059-01-0 is a valid CAS Registry Number.