The CAS Registry Mumber 28140-05-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 2,8,1,4 and 0 respectively; the second part has 2 digits, 0 and 5 respectively. Calculate Digit Verification of CAS Registry Number 28140-05: (7*2)+(6*8)+(5*1)+(4*4)+(3*0)+(2*0)+(1*5)=88 88 % 10 = 8 So 28140-05-8 is a valid CAS Registry Number.