The CAS Registry Mumber 208945-13-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 2,0,8,9,4 and 5 respectively; the second part has 2 digits, 1 and 3 respectively. Calculate Digit Verification of CAS Registry Number 208945-13: (8*2)+(7*0)+(6*8)+(5*9)+(4*4)+(3*5)+(2*1)+(1*3)=145 145 % 10 = 5 So 208945-13-5 is a valid CAS Registry Number.