N

N .

.

.

! : 1, 2, 3, 4, 5, 6, 7, 8, 9,10 :

{1, 2, 3, 4, 5, 6, 7, 8, 9, 10} {1, 2, ...,10}

2, 10.

{ ... } - ,

1, 2 , ... 10 -

! , = {10, 20, ...,100}

20 ,

20 ,

..

7 ,

7 ,

..

! 3, 11 :

= {10, 9, 8, 7, 6, 5, 4}

= {8, 9, 10, 4, 6, 5, 7} = {4, 5, 6, 7, 8, 9, 10} = {4, 5, ...,10}

, , , .

, . .

= {1, 2, ...,1000} = {2000, 4000, ...,1 000 000}

! .

: :

9 999 999 999 9 999 999 999 + 1= 10 000 000 000

10 000 000 000 + 1 = 10 000 000 00110 000 000 001 + 1 = 10 000 000 00210 000 000 000 000 000 000 000 000 00010 000 000 000 000 000 000 000 000 001

, , N .

N = {1, 2, . . .,n, }

" " .

.

N0. N0 = {0, 1, 2, . . .,n, } N

! .

X + 2 000 = 5 000X = 5 000 2 000X = 3 000

3000, X + 2 000 = 5 000

.X+2 000=50003 0004 000 !/

X ! , .X > 2 000

2 000.

= {2 001, 2 002, ...} x {2 001, 2 002, ...}

2 001>2 0002 0022 0033 0008 000 !