You can use integer counters to model 63.
–
–
(
–
)
Start with 6 negative counters.
Then take away 3 negative counters.
Subtract.
–
–
(
–
)
=
ref_doc_title.
Jumping to level 1 of 1
Excellent!
Now entering the Challenge Zone—are you ready?
Now entering the Challenge Zone—are you ready?