Chương trình cho các bạn tham khảo!
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Program FNG;
Uses crt;
Type bignum = Ansistring;
Var St,so: bignum;
n,i: longint;
Function add(a,b: bignum): bignum;
Var sum,carry,i: longint;
c: bignum;
Begin
carry:=0; c:='';
While length(a)<length(b) do a:='0'+a;
While length(b)<length(a) do b:='0'+b;
For i:=length(a) downto 1 do
Begin
sum:=Ord(A[i])-48 + Ord(B[i])-48 + carry;
carry:=sum div 10;
c:=chr(sum mod 10+ 48) + c;
End;
If carry>0 then c:='1'+c;
add:=c;
End;
Function multiply1(a: bignum; b: longint): bignum;
Var i: longint;
carry,s: longint;
c,tmp: bignum;
Begin
c:='';
carry:=0;
For i:=length(a) downto 1 do
Begin
s:=(Ord(A[i])-48)*b + carry;
carry:=s div 10;
c:=chr(s mod 10+48)+c;
End;
If carry>0 then Str(carry,tmp) else tmp:='';
multiply1:=tmp+c;
End;
Function multiply2(a,b: bignum): bignum;
Var sum,tmp: bignum;
m,i,j: longint;
Begin
m:=-1;
sum:='';
For i:=length(a) downto 1 do
Begin
m:=m+1;
tmp:=multiply1(b,Ord(A[i])-48);
For j:=1 to m do tmp:=tmp+'0';
sum:=add(tmp,sum);
End;
multiply2:=sum;
End;
Begin
Clrscr;
Write('Nhap n: '); Readln(n);
St:='1';
For i:=1 to n do
Begin
Str(i,so);
St:=Multiply2(St,so);
End;
Write(n,'! = ',St);
Readln
End.
