a)
uses crt;
var n,m,i:longint;
begin
clrscr;
write('Nhap so nguyen duong n: ');readln(n);
write('Nhap so nguyen duong m: ');readln(m);
i:=n;
while (n mod i<>0)or(m mod i<>0) do dec(i);
writeln('UCLN(',n,',',m,')=',i);
readln
end.
b)
uses crt;
var n,m,i:longint;
begin
clrscr;
write('Nhap so nguyen duong n: ');readln(n);
write('Nhap so nguyen duong m: ');readln(m);
i:=n;
while (i mod n<>0)or(i mod m<>0) do inc(i);
writeln('BCNN(',n,',',m,')=',i);
readln
end.
c)
uses crt;
var n,i:longint; s:real;
begin
clrscr;
write('Nhap so nguyen duong n: ');readln(n);
s:=0;
for i:=1 to n do s:=s+1/i;
writeln('s=',s:0:2);
readln
end.
d)
uses crt;
var n,i:longint;
begin
clrscr;
write('Nhap so nguyen duong n: ');readln(n);
i:=2;
while(n>1)and(n mod i<>0)do inc(i);
if i=n then writeln('n la so nguyen to') else writeln('n khong la so nguyen to');
readln
end.
