Solution 1

``````print("Hello World")

# The `len` function
print("Length of the string RMOTR:")
length_of_rmotr = len('RMOTR')
print(length_of_rmotr)

# The `sum` function
print("Sum of the first 5 numbers")
sum_of_first_5 = sum([1, 2, 3, 4, 5])
print(sum_of_first_5)

# Use the `len` function to replace -1 with the length of the string "Hello World"
length_of_hello_world = len('Hello World')

# Use the `sum` function to replace -1 with the result of the sum of the first 10 numbers
# First 10 numbers being: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 (not including 0)
sum_of_first_10_numbers = sum([1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
``````

# Invoking Functions

The first step to understand functions from a practical standpoint is using them. The fancy tech name we give to the action of "using" a function is "invoke a function". Python has many functions that we can just use out of the box. For example, `print` is a function (check the notes below) that lets you send characters to the console. Let's see a few different examples of invoking the `print` function:

``````print("Hello World")
print(42)

my_name = "Santiago"
print(my_name)

print("Santiago")
``````

In this case, the function name is `print`. The only parameter that it receives is "something to print". So we invoke `print` passing as an argument that thing that we want to print in the screen.

Check the examples in the editor and complete the assignment: use the `len` and `sum` function to calculate `length_of_hello_world` and `sum_of_first_10_numbers`.

### Test Cases

test length of hello world -

``````def test_length_of_hello_world():
assert length_of_hello_world == 11
``````

test sum of first 10 numbers -

``````def test_sum_of_first_10_numbers():
assert sum_of_first_10_numbers == 55
``````
print("Hello World") # The `len` function print("Length of the string RMOTR:") length_of_rmotr = len('RMOTR') print(length_of_rmotr) # The `sum` function print("Sum of the first 5 numbers") sum_of_first_5 = sum([1, 2, 3, 4, 5]) print(sum_of_first_5) # Your assignments: # Use the `len` function to replace -1 with the length of the string "Hello World" length_of_hello_world = -1 # Use the `sum` function to replace -1 with the result of the sum of the first 10 numbers # First 10 numbers being: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 (not including 0) sum_of_first_10_numbers = -1