a.
program phuongt;
uses crt;
var n: integer;
function gt(n: integer): longint;
begin
if n=1 then gt:=1 else gt:=n*gt(n-1);
end;
begin
clrscr;
write('Nhap n = '); readln(n);
write('Giai thua = ',gt(n));
readln
end.
b.
program phuongt;
uses crt;
var a, b: integer;
function mucoso: integer;
var i, k: integer;
begin
k:=1;
for i:=1 to b do k:=a*k;
mucoso:=k;
end;
begin
clrscr;
write('Nhap a = '); readln(a);
write('Nhap b = '); readln(b);
write(a, ' mu ', b, ' = ', mucoso);
readln
end.
c.
program phuongt;
uses crt;
var n, k: integer;
function thc: real;
var i, d, m, s: integer;
begin
d:=1;
for i:=1 to n do d:=d*i;
s:=1;
for i:=1 to n-k do s:=s*i;
m:=1;
for i:=1 to k do m:=m*i;
thc:=d/(s*m);
end;
begin
clrscr;
write('Nhap n = '); readln(n);
write('Nhap k = '); readln(k);
write('To hop chap ', k, ' cua ', n, ' la: ', thc:3:2);
readln
end.
