The CAS Registry Mumber 244184-56-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 2,4,4,1,8 and 4 respectively; the second part has 2 digits, 5 and 6 respectively. Calculate Digit Verification of CAS Registry Number 244184-56: (8*2)+(7*4)+(6*4)+(5*1)+(4*8)+(3*4)+(2*5)+(1*6)=133 133 % 10 = 3 So 244184-56-3 is a valid CAS Registry Number.