The CAS Registry Mumber 105054-62-4 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,5,0,5 and 4 respectively; the second part has 2 digits, 6 and 2 respectively. Calculate Digit Verification of CAS Registry Number 105054-62: (8*1)+(7*0)+(6*5)+(5*0)+(4*5)+(3*4)+(2*6)+(1*2)=84 84 % 10 = 4 So 105054-62-4 is a valid CAS Registry Number.