The CAS Registry Mumber 18802-06-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,8,8,0 and 2 respectively; the second part has 2 digits, 0 and 6 respectively. Calculate Digit Verification of CAS Registry Number 18802-06: (7*1)+(6*8)+(5*8)+(4*0)+(3*2)+(2*0)+(1*6)=107 107 % 10 = 7 So 18802-06-7 is a valid CAS Registry Number.