The CAS Registry Mumber 1546-68-5 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 1,5,4 and 6 respectively; the second part has 2 digits, 6 and 8 respectively. Calculate Digit Verification of CAS Registry Number 1546-68: (6*1)+(5*5)+(4*4)+(3*6)+(2*6)+(1*8)=85 85 % 10 = 5 So 1546-68-5 is a valid CAS Registry Number.