*for..do
Program HOC24;
var i,n: integer;
s: real;
begin
write('Nhap n: '); readln(n);
s:=0;
for i:=1 to n do s:=s+1/sqr(i);
write('S= ',s:6:2);
readln
end.
*while..do
Program HOC24;
var i,n: integer;
s: real;
begin
write('Nhap n: '); readln(n);
i:=1;
while i<=n do
begin
s:=s+1/sqr(i);
i:=i+1;
end;
write('S= ',s:6:2);
readln
end.