The CAS Registry Mumber 2543-14-8 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 2,5,4 and 3 respectively; the second part has 2 digits, 1 and 4 respectively. Calculate Digit Verification of CAS Registry Number 2543-14: (6*2)+(5*5)+(4*4)+(3*3)+(2*1)+(1*4)=68 68 % 10 = 8 So 2543-14-8 is a valid CAS Registry Number.