The CAS Registry Mumber 2546-67-0 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 6 respectively; the second part has 2 digits, 6 and 7 respectively. Calculate Digit Verification of CAS Registry Number 2546-67: (6*2)+(5*5)+(4*4)+(3*6)+(2*6)+(1*7)=90 90 % 10 = 0 So 2546-67-0 is a valid CAS Registry Number.