The CAS Registry Mumber 5919-31-3 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 5,9,1 and 9 respectively; the second part has 2 digits, 3 and 1 respectively. Calculate Digit Verification of CAS Registry Number 5919-31: (6*5)+(5*9)+(4*1)+(3*9)+(2*3)+(1*1)=113 113 % 10 = 3 So 5919-31-3 is a valid CAS Registry Number.