Order of Operations: PEMDAS vs BODMAS
Different acronyms, different countries — the exact same rule. Here's what each letter means and how to apply it.
PEMDAS (USA), BODMAS (UK/India/Australia), BEDMAS (Canada) — all the same rule: (1) Brackets/Parentheses first, (2) Exponents/Orders, (3) Multiplication and Division left to right, (4) Addition and Subtraction left to right. Example: 3 + 6 × 2 = 3 + 12 = 15 (not 9 × 2 = 18). Multiplication before addition, always.
| Acronym | Country | Letters stand for |
|---|---|---|
| PEMDAS | 🇺🇸 USA | Parentheses, Exponents, Multiplication, Division, Addition, Subtraction |
| BODMAS | 🇬🇧 UK / 🇮🇳 India / 🇦🇺 Australia | Brackets, Orders, Division, Multiplication, Addition, Subtraction |
| BIDMAS | 🇬🇧 UK (alternative) | Brackets, Indices, Division, Multiplication, Addition, Subtraction |
| BEDMAS | 🇨🇦 Canada | Brackets, Exponents, Division, Multiplication, Addition, Subtraction |
| GEMDAS | Some curricula | Grouping, Exponents, Multiplication, Division, Addition, Subtraction |
Note: BODMAS lists Division before Multiplication but they are equal priority — work left to right. Same for PEMDAS. This is the most common point of confusion.
The Four Rules — in Order
Solve everything inside () or [] or {} before touching anything outside. If nested, work from innermost outward. Example: 2 × (3 + (4 − 1)) → 2 × (3 + 3) → 2 × 6 = 12.
Calculate any powers (²) or roots (√) next. Example: 2 + 3² = 2 + 9 = 11 (not 5² = 25). The exponent belongs only to the 3, not to the result of the addition.
These two operations have EQUAL priority. Work left to right. Critical: 12 ÷ 4 × 3 = 3 × 3 = 9. NOT 12 ÷ 12 = 1. Always process whichever of × or ÷ comes first reading left to right.
These two operations have EQUAL priority. Work left to right. Example: 10 − 3 + 2 = 7 + 2 = 9. NOT 10 − 5 = 5. The subtraction goes first because it appears first.
Worked Examples
| Expression | Step-by-step | Answer |
|---|---|---|
| 3 + 6 × 2 | 3 + (6 × 2) = 3 + 12 | 15 |
| (3 + 6) × 2 | 9 × 2 | 18 |
| 2³ + 4 ÷ 2 | 8 + 2 | 10 |
| 20 − 4 × 3 + 1 | 20 − 12 + 1 = 8 + 1 | 9 |
| (5 + 3)² ÷ 4 | 8² ÷ 4 = 64 ÷ 4 | 16 |
| 100 ÷ 5 × 2 | 20 × 2 (left to right) | 40 |