Multiply/divide

Add multiply, divide and zero check.

Multiplication and division

Now we'll add multiplication and division to the calculator. These functions use the same structure:

def multiply(x, y):
    return x * y

def divide(x, y):
    return x / y

Multiplication uses *, division uses /. The division result is always a float: 10 / 5 gives 2.0.

Division has one problem: if the second number is zero, you get ZeroDivisionError. To prevent this we'll learn if and try/except in the next lesson.

Zero check (if)

Division by zero raises an error. The first way to prevent this is to check with if:

def divide(x, y):
    if y == 0:
        return 0
    return x / y

The if y == 0: line runs the indented block when y is zero. == is an equality comparison. We'll cover if in detail in a separate group.

Exercise Add multiplication and division

The previous functions are ready. Now add the multiply(x, y) and divide(x, y) functions (divide should have an if y == 0: return 0 check). Then print print(multiply(a, b)) and print(divide(a, b)).

Show example solution

def multiply(x, y):
    return x * y
def divide(x, y):
    if y == 0:
        return 0
    return x / y
print(multiply(a, b))
print(divide(a, b))

Test yourself

What is the result of 10 / 5?
- 2
- 5
- 2.0
- It raises an error
Show answer

2.0 — Division always returns a float: 2.0.

Complete the multiply function

def multiply(x, y):
    return x ____ y

Show answer

def multiply(x, y):
    return x * y

Match the operators

+

Addition
-

Subtraction
*

Multiplication
/

Division

Next lesson: Error handling

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