The CAS Registry Mumber 35261-49-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 3,5,2,6 and 1 respectively; the second part has 2 digits, 4 and 9 respectively. Calculate Digit Verification of CAS Registry Number 35261-49: (7*3)+(6*5)+(5*2)+(4*6)+(3*1)+(2*4)+(1*9)=105 105 % 10 = 5 So 35261-49-5 is a valid CAS Registry Number.