Check if Number is Less Than or Equal to Zero

1. The Challenge: Boolean Comparison

Create a function less_than_or_equal_to_zero(num) that takes a number as its only argument and returns True if it's less than or equal to zero, otherwise return False.

2. Why It Matters

Boolean comparison operators (<, <=, >, >=, ==, !=) are the decision-making engine behind conditional control flow in Python.

3. The Python Solution

Use the <= comparison operator, which returns a boolean True or False:

def less_than_or_equal_to_zero(num):
    return num <= 0

# Testing our function
print(less_than_or_equal_to_zero(5))  # Output: False
print(less_than_or_equal_to_zero(0))  # Output: True
print(less_than_or_equal_to_zero(-2)) # Output: True

4. Python Boolean Principles

In Python, booleans are capitalized: True and False (unlike JavaScript's lowercase true and false).

5. Common Mistakes

• Unnecessary If/Else Wrap: Writing if num <= 0: return True else: return False is redundant! The expression num <= 0 ALREADY evaluates directly to a boolean True or False. Return the expression directly!
• Confusing = with ==: Single = is for variable assignment. Double == or <= is for equality and comparison.

6. Next Steps

Return boolean expressions directly. Next, let's solve the Farm Problem animal legs challenge!