Answer:
Explanation:
you can draw a table that has 7 rows and 7 columns, put the 6 numbers and their difference( 1-1=0, 1-2= -1, 1-3= -2,...)
- 1 2 3 4 5 6
1 0 1 2 3 4 5
2 -1 0 1 2 3 4
3 -2 -1 0 1 2 3
4 -3 -2 -1 0 1 2
5 -4 -3 -2 -1 0 1
6 -5 -4 -3 -2 -1 0