The CAS Registry Mumber 6183-27-3 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 6,1,8 and 3 respectively; the second part has 2 digits, 2 and 7 respectively. Calculate Digit Verification of CAS Registry Number 6183-27: (6*6)+(5*1)+(4*8)+(3*3)+(2*2)+(1*7)=93 93 % 10 = 3 So 6183-27-3 is a valid CAS Registry Number.