The CAS Registry Mumber 65419-31-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,5,4,1 and 9 respectively; the second part has 2 digits, 3 and 1 respectively. Calculate Digit Verification of CAS Registry Number 65419-31: (7*6)+(6*5)+(5*4)+(4*1)+(3*9)+(2*3)+(1*1)=130 130 % 10 = 0 So 65419-31-0 is a valid CAS Registry Number.