Operator Precedence

1.6. Operator Precedence#

What is 8/2(2+2)?

PEMDAS: “Please Excuse My Dear Aunt Sally”

Order of precedence:

  1. Parentheses

  2. Exponents

  3. Multiplication and division (left to right)

  4. Addition and subtraction (left to right)

1.6.1. Precedence in Python#

  1. Parentheses

  2. Exponentiation ** (right to left)

  3. Unary plus +x, unary minus -x

  4. Multiplication *, division /, floor division //, modulo % (left to right)

  5. Addition +, subtraction -

1.6.2. Ambiguity in 8/2(2+2)#

The expression 8/2(2+2) is ambiguous. Under standard precedence (and Python’s rules), it’s parsed as:

8 / 2 * (2 + 2)

Some readers might interpret 2(2+2) as implicit multiplication forming a single term:

8 / (2 * (2 + 2))

To avoid ambiguity, always add parentheses to make the intended order explicit.

1.6.3. What’s potentially unclear about 212 - 32 * 5 / 9?#

The expression is valid, but the intent may be unclear to readers. Parentheses improve readability:

212 - (32 * 5 / 9)

This makes it obvious that the multiplication and division occur before the subtraction.

1.6.4. Best practice#

Use parentheses to clarify complex expressions, even when not strictly necessary. Clear grouping improves readability and reduces errors.

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