cú pháp: var <danh sách biến>: boolean;
VD:
var kt: boolean;
i,n,d: integer;
begin
clrscr;
write ('nhap n: '); readln (n);
for i:=1 to n do if n mod i=0 then d:=d+1;
if d=2 then kt:=true else kt:=false;
if kt=true then write (n,' la snt')
else (n,' khong phai la so nguyen to');
readln;
end.