# Learn Recursion by Solving the Tower of Hanoi Puzzle - Step 19

### Tell us what’s happening:

It says to change the if function to add remainder, that’s exactly what I did and I keep getting an error…

``````NUMBER_OF_DISKS = 3
number_of_moves = 2**NUMBER_OF_DISKS - 1
rods = {
'A': list(range(NUMBER_OF_DISKS, 0, -1)),
'B': [],
'C': []
}

# User Editable Region

def move(n, source, auxiliary, target):
# display starting configuration
print(rods)
for i in range(number_of_moves):
remainder = (i + 1) % 3
if remainder:
print(f'Move {i + 1} allowed between {source} and {target}')

# User Editable Region

# initiate call from source A to target C with auxiliary B
move(NUMBER_OF_DISKS, 'A', 'B', 'C')
``````

User Agent is: `Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.2.1 Safari/605.1.15`

### Challenge Information:

Learn Recursion by Solving the Tower of Hanoi Puzzle - Step 19

You appear to have created this post without editing the template. Please edit your post to Tell us what’s happening in your own words.

The wording is a bit vague, but you want to replace the part of the expression that the `remainder` variable is now equal to.

`remainder = (i + 1) % 3`

So if the `remainder` is equal to 1 the if should execute.

Since you’ve assigned `(i + 1) % 3` to the variable `remainder` you can replace `(i + 1) % 3` with `remainder` in the `if` condition.

2 Likes

Got it! I appreciate your help on this one!

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