The CAS Registry Mumber 251989-02-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 2,5,1,9,8 and 9 respectively; the second part has 2 digits, 0 and 2 respectively. Calculate Digit Verification of CAS Registry Number 251989-02: (8*2)+(7*5)+(6*1)+(5*9)+(4*8)+(3*9)+(2*0)+(1*2)=163 163 % 10 = 3 So 251989-02-3 is a valid CAS Registry Number.