Symbol First use Meaning
| | Chapter 4 Symbol for absolute value (of quantity between bars)
− Chapter 4 Conventional symbol for subtraction
[ ] Chapter 4 Brackets for grouping of quantities
· Chapter 5 Alternative symbol for multiplication
÷ Chapter 5 Alternative symbol for division
≠ Chapter 5 Symbol meaning “is not equal to”
: Chapter 6 Symbol for a ratio or proportion
Chapter 6 Inequality symbol meaning “is strictly larger than”
< Chapter 6 Inequality symbol meaning “is strictly smaller than”
≥ Chapter 6 Symbol meaning “is larger than or equal to”
≤ Chapter 6 Symbol meaning “is smaller than or equal to”
{ } Chapter 6 Braces for grouping of quantities
. Chapter 7 Decimal point
Σ Chapter 7 Uppercase Greek sigma symbol for sum
± Chapter 8 Plus-or-minus sign
√ Chapter 8 Surd symbol for square root
⇒ Chapter 11 Symbol meaning “implies” or “if/then”
⇔ Chapter 11 Symbol meaning “if and only if ”
Δ Chapter 15 Uppercase Greek delta symbol for difference
f−^1 Chapter 17 Notation for inverse of a function f
718 Special Characters in Order of Appearance