By mathematica:
Clear["`*"];
Do[x[i]=Input["Enter the value of x"];
y[i][1]=Input["Enter the corresponding value of y"],{i,1,4}];
divided[r_,q_]:=Module[{x1=r,n=q},ans=0;
Do[ex=1;
Do[If[ij,ex=ex((x1-x[j])/(x[i]-x[j]))],{j,1,n}];
ans=ans+(ex)y[i][1],{i,1,n}];
Print["Recquired Result : ",ans//N]];
divided[301,4];