The CAS Registry Mumber 93758-28-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,3,7,5 and 8 respectively; the second part has 2 digits, 2 and 8 respectively. Calculate Digit Verification of CAS Registry Number 93758-28: (7*9)+(6*3)+(5*7)+(4*5)+(3*8)+(2*2)+(1*8)=172 172 % 10 = 2 So 93758-28-2 is a valid CAS Registry Number.