bài 1:
câu a:
program oken;
uses crt;
var i,n,a:longint;
begin
clrscr;
write('nhap so n: '); readln(n);
for i:=1 to n do
a:= a+i;
writeln('A= ',a);
readln;
end.
câu b:
program oken;
uses crt;
var c,i,n:longint;
begin
clrscr;
write('nhap n: '); readln(n);
for i:=1 to n do
if i mod 2 = 0 then c:=c+i;
writeln('C= ',c);
readln;
end.
câu c:
program oken;
uses crt;
var e,n,i:longint;
begin
clrscr;
write('nhap n'); readln(n);
for i:=1 to n
if i mod 2 =1 then e:=e+i;
writeln('E= ',e);
readln;
end.