If you've ever wondered what please excuse my dear aunt sally means, you're not alone. This phrase is a popular mnemonic that helps students remember the order of operations in mathematics. In practice, in this article, we explore the origins, each component's role, and practical tips for using the mnemonic effectively. Whether you're a student struggling with math problems, a teacher looking for engaging memory aids, or simply curious about the phrase itself, you'll find a thorough breakdown of please excuse my dear aunt sally and how it fits into everyday calculations.
The Origin of the Mnemonic
The expression please excuse my dear aunt sally emerged in the early 20th century as a catchy way to teach the order of operations in arithmetic and algebra. As textbooks began to standardize the sequence, educators needed a simple, memorable phrase that students could easily recall. The resulting mnemonic—Please Excuse My Dear Aunt Sally—stood for the six fundamental steps: Parentheses, Exponents, Multiplication, Division, Addition, and Subtraction. Before standardized rules existed, mathematicians often relied on parentheses and verbal cues to clarify which operations should be performed first. Over time, variations like Please My Dear Aunt Sally (omitting "Excuse") have appeared, but the original version remains the most widely taught.
Breaking Down Each Element
P – Parentheses (or Brackets)
Parentheses are the first priority in any calculation. They group numbers or expressions that must be evaluated before any other operation. To give you an idea, in the expression 3 × (4 + 2), the addition inside the parentheses (4 + 2 = 6) is performed first, resulting in 3 × 6 = 18. Without parentheses, the order would differ, leading to a different result Small thing, real impact. But it adds up..
E – Exponents (or Powers)
After handling parentheses, the next step is to resolve exponents. An exponent indicates repeated multiplication of a base number. In 5 + 2^3, the exponent is calculated first: 2^3 = 8, then the addition: 5 + 8 = 13. Exponents can also appear within parentheses, in which case they are solved while still inside the grouped expression.
M – Multiplication
Multiplication and division share the same priority level and are performed from left to right as they appear. What this tells us is in 12 ÷ 3 × 2, you first divide 12 ÷ 3 = 4, then multiply 4 × 2 = 8. It’s crucial to remember that multiplication does not automatically take precedence over division; the left‑to‑right rule applies.
D – Division
Division follows the same left‑to‑right rule as multiplication. In expressions like 20 ÷ 4 × 5, you first divide 20 ÷ 4 = 5, then multiply 5 × 5 = 25. This ensures consistency and avoids ambiguity when multiple operations of equal rank appear.
A – Addition
Addition and subtraction also share equal priority and are executed left to right. Take this: in 9 + 6 - 3, you add first: 9 + 6 = 15, then subtract: 15 - 3 = 12. Keeping this order prevents common errors where students might incorrectly perform subtraction before addition.
S – Subtraction
Subtraction completes the sequence. Using the same example, after addition, the subtraction step finalizes the result. Understanding that subtraction is not a higher‑priority operation helps students avoid misplacing the sign or incorrectly grouping terms.
How to Apply Please Excuse My Dear Aunt Sally in Real Problems
- Identify the expression and write down the steps indicated by the mnemonic.
- Solve parentheses first, simplifying any inner operations.
- Handle exponents within the simplified parentheses or the whole expression.
- Proceed with multiplication and division from left to right.
- Finish with addition and subtraction from left to right.
- Check your work by re‑evaluating the expression or using a calculator to verify the result.
Example Walk‑Through
Consider the problem: 4 × (3 + 2^2) - 6 ÷ 3 + 1 Small thing, real impact..
- Parentheses: Inside the parentheses, first the exponent
2^2 = 4, then addition3 + 4 = 7. The expression becomes4 × 7 - 6 ÷ 3 + 1. - Multiplication:
4 × 7 = 28. New expression:28 - 6 ÷ 3 + 1. - Division:
6 ÷ 3 = 2. Expression:28 - 2 + 1. - Addition:
28 - 2 = 26, then26 + 1 = 27.
The final answer is 27. Following the mnemonic ensures each step is performed in the correct order And that's really what it comes down to..
Common Pitfalls and How to Avoid Them
- Ignoring left‑to‑right rule: Students often think multiplication always comes before division. Remember that they are equal; process them as they appear.
- Misplacing parentheses: A misplaced or missing parenthesis can completely change the outcome. Always double‑check grouping symbols.
- Confusing exponents with multiplication: An exponent is not the same as multiplying the base by a number. To give you an idea,
2^3is2 × 2 × 2, not2 × 3.