The CAS Registry Mumber 26740-19-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 2,6,7,4 and 0 respectively; the second part has 2 digits, 1 and 9 respectively. Calculate Digit Verification of CAS Registry Number 26740-19: (7*2)+(6*6)+(5*7)+(4*4)+(3*0)+(2*1)+(1*9)=112 112 % 10 = 2 So 26740-19-2 is a valid CAS Registry Number.