The CAS Registry Mumber 107343-19-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,7,3,4 and 3 respectively; the second part has 2 digits, 1 and 9 respectively. Calculate Digit Verification of CAS Registry Number 107343-19: (8*1)+(7*0)+(6*7)+(5*3)+(4*4)+(3*3)+(2*1)+(1*9)=101 101 % 10 = 1 So 107343-19-1 is a valid CAS Registry Number.