The CAS Registry Mumber 107741-39-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,7,7,4 and 1 respectively; the second part has 2 digits, 3 and 9 respectively. Calculate Digit Verification of CAS Registry Number 107741-39: (8*1)+(7*0)+(6*7)+(5*7)+(4*4)+(3*1)+(2*3)+(1*9)=119 119 % 10 = 9 So 107741-39-9 is a valid CAS Registry Number.