The CAS Registry Mumber 26239-04-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 2,6,2,3 and 9 respectively; the second part has 2 digits, 0 and 4 respectively. Calculate Digit Verification of CAS Registry Number 26239-04: (7*2)+(6*6)+(5*2)+(4*3)+(3*9)+(2*0)+(1*4)=103 103 % 10 = 3 So 26239-04-3 is a valid CAS Registry Number.