A minus sign placed immediately before a variable tells you to reverse the sign of the value of

the variable. Therefore, –x means that if x is positive, you should now make it negative. But it also

means that if x is negative, make it positive (so, if x was –5 kg, then –x would be 5 kg). Used this

way, the minus sign is referred to as a unary operator because it’s acting on only one variable.

Multiplication

The word term is generic for an individual item or element in a formula. Multiplication of terms is

indicated in several ways, as shown in Table 2-1.

TABLE 2-1 Multiplication Options

What It Is

Example

Where It’s Used

Asterisk

Plain text formulas, but almost never in typeset formulas

Cross

Typeset formula, between two variables or two constants being

multiplied together

Raised dot

Typeset formula

Term is immediately in front of a parenthesized

expression

Typeset formula

Brackets and curly braces

Typeset formula containing “nested” parentheses

Two or more terms running together

In typeset formulas only

You can put terms right next to each other to imply multiplication only when it’s perfectly clear

from the context of the formula that the authors are using only single-letter variable names (like x

and y), and that they’re describing calculations where it makes sense to multiply those variables

together. In other words, you can’t put numeric terms right after one another to imply

multiplication, meaning you can’t replace 5 × 3 with 53, because 53 is an actual number itself.

And you shouldn’t replace variables like length × width with lengthwidth, because it looks like

you’re referring to a single variable named lengthwidth.

Division

Like multiplication, division can be indicated in several ways:

With a slash (/) in plain text formulas: Distance/Time

With a division symbol (÷) in typeset formulas: Distance ÷ Time

With a long horizontal bar in typeset formulas:

Powers, roots, and logarithms

In the next section, we cover powers, roots, and logarithms, all three of which are related to the idea

of repeated multiplication.

Raising to a power

Raising to a power is a shorthand way to indicate repeated multiplication by the same number. You