The CAS Registry Mumber 111690-62-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,1,6,9 and 0 respectively; the second part has 2 digits, 6 and 2 respectively. Calculate Digit Verification of CAS Registry Number 111690-62: (8*1)+(7*1)+(6*1)+(5*6)+(4*9)+(3*0)+(2*6)+(1*2)=101 101 % 10 = 1 So 111690-62-1 is a valid CAS Registry Number.