The CAS Registry Mumber 116405-68-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,6,4,0 and 5 respectively; the second part has 2 digits, 6 and 8 respectively. Calculate Digit Verification of CAS Registry Number 116405-68: (8*1)+(7*1)+(6*6)+(5*4)+(4*0)+(3*5)+(2*6)+(1*8)=106 106 % 10 = 6 So 116405-68-6 is a valid CAS Registry Number.