The CAS Registry Mumber 1882-73-1 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 1,8,8 and 2 respectively; the second part has 2 digits, 7 and 3 respectively. Calculate Digit Verification of CAS Registry Number 1882-73: (6*1)+(5*8)+(4*8)+(3*2)+(2*7)+(1*3)=101 101 % 10 = 1 So 1882-73-1 is a valid CAS Registry Number.