9.
program Tin_hoc;
uses crt;
var i,a,b,tong:integer;
begin
writeln('Nhap a:');readln(a);
writeln('Nhap b:');readln(b);
tong:=a+b;
if (tong>0) and (tong mod 3 = 0) then
writeln('Tong cua a va b la so nguyen duong va chia het cho 3');
if (tong<=0) and (tong mod 3 = 0) then
writeln('Tong cua a va b khong la so nguyen duong va chia het cho 3');
if (tong>0) and (tong mod 3 <> 0) then
writeln('Tong cua a va b la so nguyen duong va khong chia het cho 3');
readln;
end.
10.
program Tin;
uses crt;
var i,n:integer;
tong:real;
begin
clrscr;
write('Nhap n: ');readln(n);
tong:=0;
for i:= 1 to n do tong:= tong + 1/i;
writeln('S=',tong:0:2);
readln;
end.
for
