Leading zeros are extra zeros to the left of a number when you want to have a regular amount of digits in a set of numbers.
For instance, `0001`

, `0002`

, and `0003`

is a good formatting if you think you'll get to have thousands of entries, as you can stay at four digits up to `9999`

.

```
# Define your number
number = 1
two_digits = f'{number:02d}'
# 01
four_digits = f'{number:04d}'
# 0001
```

We use the Python formatting helper `{my_number:04d}`

to enforce a minimum set of digits in our number variable.
This means you can use it to set the value of a string or to create or print a longer string with that number, not necessarily having to store its value.

```
a_number = 42
print(f'The number is {a_number:06d}.')
# The number is 000042.
print(f'The number is {512:06d}.')
# The number is 000512.
```