Counting the number of entries in a dictionary
To count the number of entries in a dictionary, we can use the `len()` function in Python. In this case, we have a dictionary with keys as names and values as ages:
python
d = {'John': 40, 'Peter': 45}

Using the len() function
To obtain the number of entries in this dictionary, we can simply use the `len()` function:
python
num_entries = len(d)
print(num_entries)
This will output `2`, as there are two key-value pairs in the dictionary.

Explanation:
- The `len()` function returns the number of items in a container, in this case, the number of key-value pairs in the dictionary.
- When we pass the dictionary `d` to the `len()` function, it counts the number of entries in the dictionary and returns the count.
- In our example, the dictionary `d` has two entries ('John': 40 and 'Peter': 45), so the `len()` function returns `2`.

Conclusion:
By using the `len()` function in Python, we can easily obtain the number of entries in a dictionary. This can be useful for various applications where we need to know the size of the dictionary.