Program BTH;
uses crt;
var n,i,k:longint;
function tong(a,b,c:longint):longint;
    Begin
        tong:=a+b+c;
    end;
function tich(a,b,c:longint):longint;
    Begin
        tich:=a*b*c;
    end;
Begin
    clrscr;
    write('Nhap so thu 1: ');readln(n);
    write('Nhap so thu 2: ');readln(i);
    write('Nhap so thu 3: ');readln(k);
    writeln('Tong 3 so tren la: ',tong(n,i,k));
    writeln('Tich 3 so tren la: ',tich(n,i,k));
    readln;
end.

program kiemtra;
uses crt;
var x, y, z:longint;
function tong (a,b,c:longint):longint;
begin
     tong:=a+b+c;
end;
function tich (a,b,c:longint):longint;
begin
     tich:=a*b*c;
end;
begin clrscr;
     write ('Nhap vao ba so: '); readln (x, y, z);
     writeln ('Tong 3 so do la: ',tong (x, y, z));
     writeln ('Tich 3 so do la: ',tich(x, y, z));

readln;
end.

Học tốt!