The CAS Registry Mumber 66250-04-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,6,2,5 and 0 respectively; the second part has 2 digits, 0 and 4 respectively. Calculate Digit Verification of CAS Registry Number 66250-04: (7*6)+(6*6)+(5*2)+(4*5)+(3*0)+(2*0)+(1*4)=112 112 % 10 = 2 So 66250-04-2 is a valid CAS Registry Number.