The CAS Registry Mumber 104431-07-4 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,4,4,3 and 1 respectively; the second part has 2 digits, 0 and 7 respectively. Calculate Digit Verification of CAS Registry Number 104431-07: (8*1)+(7*0)+(6*4)+(5*4)+(4*3)+(3*1)+(2*0)+(1*7)=74 74 % 10 = 4 So 104431-07-4 is a valid CAS Registry Number.