The CAS Registry Mumber 68690-49-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,8,6,9 and 0 respectively; the second part has 2 digits, 4 and 9 respectively. Calculate Digit Verification of CAS Registry Number 68690-49: (7*6)+(6*8)+(5*6)+(4*9)+(3*0)+(2*4)+(1*9)=173 173 % 10 = 3 So 68690-49-3 is a valid CAS Registry Number.