I have now put in evalf before Pi

f:=x->4/(1+x^2);

n:=1;s[n]:=1;while abs(s[n]-evalf(Pi))>=0.0001 do n:=n+1;s[n]:=evalf(sum(f((k-1)/n+k/n)*1/2n),k=1..n));end do; E[n]:=evalf(abs(s[n]-Pi))

but still no....

This is the operation I've done

f:=x->4/(1+x^2);

n:=1;s[n]:=1;while abs(s[n]-Pi)>=0.0001 do n:=n+1;s[n]:=evalf(sum(f((k-1)/n+k/n)*1/2n),k=1..n));end do; E[n]:=evalf(abs(s[n]-Pi));

but it doesn't work....

I'm supposed to get the answer S[41]=3.141493506 but I don't understand what I'm doing wrong