Equations

Use an equation editor

An equation editor—for example, Word Equation Editor—is always preferred for equations, simple or complex. Use the same font, font style, and font size (including subscripts) in text when referring to elements that appear in equations.

Formatting equations

Indent the equation on its own line and introduce with the phrase “...is calculated by:”. Follow the equation with a definition of each of the variables and their units. Do not use phrases in equations like “gold price”—create a variable instead. Do not place units of measure in the equation—they are also mathematical expressions (g/t, for example) and can be confusing.

When formatting long equations, choose line breaks, where possible, that are consistent with the mathematical structure—before or after a bracketed expression, for example.

Equations in text

An equation editor is always preferred for equations. However, simple arithmetical expression can be written in text. If you mix equation objects and text equations in the same document, format the text equation exactly like the equation object (Microsoft Equation Editor applies Cambria Math font with variables in italic).

Follow the same guidelines as complex equations. Also, separate mathematical operators +, ×, – , =, and ÷ from numbers, constants and variables with spaces. Unless you are quoting programming code, do not use functions like * or SQRT—use the correct mathematical symbols.

Correct

Copper equivalent grade (CuEq) in percent (%) is calculated by:

  CuEq = Cu + Au × 0.7 + Mo × 4.0

where,

  Cu is the copper grade in percent (%)

  Mo is the molybdenum grade in percent (%)

  Au is the gold grade in grams per tonne (g/t)

Note

The multiplication symbol × is different from the letter x (and which is often used as a variable). The subtraction and negative sign symbol is the en dash (–), not the hyphen. Use the division slash ∕ or the division symbol ÷, but the forward slash / on the keyboard is acceptable. The variable sigma (Σ) and the summation symbol (∑) are also different characters.