Order of Operations (PEMDAS)

PEMDAS

P - Parentheses (and other grouping symbols) E - Exponents M/D - Multiplication and Division (left to right) A/S - Addition and Subtraction (left to right)

Memory aid: "Please Excuse My Dear Aunt Sally"

Important Notes

1. Multiplication and Division have the SAME priority - do them left to right
2. Addition and Subtraction have the SAME priority - do them left to right
3. Always work from inside out with parentheses

Grouping Symbols

All mean "do this first":

• Parentheses: $( )$
• Brackets: $[ ]$
• Braces: $\{ \}$
• Fraction bar: $\frac{a + b}{c - d}$

Nested Parentheses

Work from innermost to outermost: $3 + [2 \times (5 - 1)]$

Common Mistakes

❌ $6 + 2 \times 3 = 8 \times 3 = 24$ (Wrong!) ✅ $6 + 2 \times 3 = 6 + 6 = 12$ (Correct: multiply first)

❌ $12 \div 3 \times 2 = 12 \div 6 = 2$ (Wrong!) ✅ $12 \div 3 \times 2 = 4 \times 2 = 8$ (Correct: left to right)