The CAS Registry Mumber 104058-09-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,4,0,5 and 8 respectively; the second part has 2 digits, 0 and 9 respectively. Calculate Digit Verification of CAS Registry Number 104058-09: (8*1)+(7*0)+(6*4)+(5*0)+(4*5)+(3*8)+(2*0)+(1*9)=85 85 % 10 = 5 So 104058-09-5 is a valid CAS Registry Number.