The CAS Registry Mumber 104802-41-7 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,4,8,0 and 2 respectively; the second part has 2 digits, 4 and 1 respectively. Calculate Digit Verification of CAS Registry Number 104802-41: (8*1)+(7*0)+(6*4)+(5*8)+(4*0)+(3*2)+(2*4)+(1*1)=87 87 % 10 = 7 So 104802-41-7 is a valid CAS Registry Number.