S=1^2+2^2+…+19^2+20^2 Viết chương trình

Câu 1:

uses crt;

var s,i,n:integer;

begin

clrscr;

write('Nhap n='); readln(n);

s:=0;

for i:=0 to n do

if i mod 2=0 then s:=s+i;

writeln('S=',s);

readln;

end.

Câu 2:

uses crt;

var s:real;

i,n:integer;

begin

clrscr;

write('Nhap n='); readln(n);

s:=0;

for i:=1 to n do

s:=s+1/i;

writeln('S=',s:4:2);

readln;

end.

Câu 3:

uses crt;

var a:array[1..100]of integer;

n,i,tb:integer;

begin

clrscr;

write('Nhap n='); readln(n);

for i:=1 to n do

begin

write('A[',i,']='); readln(a[i]);

end;

tb:=0;

for i:=1 to n do

tb:=tb+a[i];

writeln('Trung binh cong=',tb/n:4:2);

readln;

end.