The CAS Registry Mumber 50910-51-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,0,9,1 and 0 respectively; the second part has 2 digits, 5 and 1 respectively. Calculate Digit Verification of CAS Registry Number 50910-51: (7*5)+(6*0)+(5*9)+(4*1)+(3*0)+(2*5)+(1*1)=95 95 % 10 = 5 So 50910-51-5 is a valid CAS Registry Number.