Bài 1:
Program Sum;
Uses crt;
Var n, res: longint;
Begin
Clrscr;
Write('Nhap n: '); Readln(n);
res := n * (n + 1) div 2;
Write('Sum = ',res);
Readln
End.
Bài 2:
Program Sum;
Uses crt;
Var n, i: longint;
res: extended;
Begin
Clrscr;
Write('Nhap n: '); Readln(n);
res:=0;
For i:=1 to n do
res := res + 1/i;
Write('Sum = ',res:0:2);
Readln
End.
Bài 3:
Program Sum;
Uses crt;
Var n, x, i: longint;
res: extended;
Begin
Clrscr;
Write('Nhap n, x: '); Readln(n, x);
res:=0;
For i:=1 to n do
res := res + x/i;
Write('Sum = ',res:0:2);
Readln
End.