The CAS Registry Mumber 104417-76-7 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,4,4,1 and 7 respectively; the second part has 2 digits, 7 and 6 respectively. Calculate Digit Verification of CAS Registry Number 104417-76: (8*1)+(7*0)+(6*4)+(5*4)+(4*1)+(3*7)+(2*7)+(1*6)=97 97 % 10 = 7 So 104417-76-7 is a valid CAS Registry Number.