-


2	3	6	7	8
		2	3	4

Step #1:

Subtract 4 from 8 to get 4.

-


2	3	6	7	8
		2	3	4

				4

Step #2:

Subtract 3 from 7 to get 4.

-


2	3	6	7	8
		2	3	4

			4	4

Step #3:

Subtract 2 from 6 to get 4.

-


2	3	6	7	8
		2	3	4

		4	4	4

Step #4:

Subtract from 3 to get 3.

-


2	3	6	7	8
		2	3	4

	3	4	4	4

Step #5:

Subtract from 2 to get 2.

-


2	3	6	7	8
		2	3	4

2	3	4	4	4

All done! The answer is:

23444