20 PART 1 Getting Started with Biostatistics

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:}

Distance

Time

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 indicate raising to a power by:»

» ^{Superscripting in typographic formulas, such as 53»}

» ^{Using ** in plain text formulas, such as 5}

3

**»

» ^{Using ^ in plain text formulas, such as 5 3}

^

All the preceding expressions are read as “five to the third power,” “five to the

power of three,” or “five cubed.” It says to multiply three fives together: 5 × 5 × 5,

which gives you 125.

Here are some other features of power:»

» ^{A power doesn’t have to be a whole number. You can raise a number to a}

fractional power (such as 3.8). You can’t visualize this in terms of repeated

multiplications, but your scientific calculator can show you that 2 6^{3 8}

.

. is equal

to approximately 37.748.