The CAS Registry Mumber 690646-00-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 6,9,0,6,4 and 6 respectively; the second part has 2 digits, 0 and 0 respectively. Calculate Digit Verification of CAS Registry Number 690646-00: (8*6)+(7*9)+(6*0)+(5*6)+(4*4)+(3*6)+(2*0)+(1*0)=175 175 % 10 = 5 So 690646-00-5 is a valid CAS Registry Number.