5613 (base 9)
+ 3678 (base 9)
Starting in the 1s column:
3+8 = 11 (base 10), so in base 9, that’s “2 carry the 1” because 11 is 2 more than 9.
In the next column:
1+7+ the 1 that was carried = 9 (base 10), so in base 9 you put a 0 and carry the 1
Next column:
6+6+1 = 13 (base 10), so in base 9 you put 4 and carry a 1, because 13 is 4 more than 9
Next column:
5+3+1 = 9 (base 10), so in base 9, you put 0 and carry a 1 to the next column
See the picture for the written work. The left part just shows the first step, while the right picture shows the entire answer.
