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# Numbers for iPad: Formulas and Functions

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Chris Fehily offers clear and to-the-point instruction on how to build charts and tables and get the most out of the Numbers spreadsheet for the iPad. In this chapter, Chris shows you how to work with formulas and functions.
This chapter is from the book

### This chapter is from the book 

After you enter and organize your data values in tables, you can use formulas and functions to reduce reams of raw numbers to meaningful information. A formula performs a calculation and displays the result in the cell where you enter the formula, called a formula cell. Formulas can do things as simple as adding two numbers, but it’s by using functions in formulas that you bring to bear Numbers’ true computing abilities. Functions are built-in, named operations, such as SUM and AVERAGE, that perform a wide range of calculations for statistics, probability, dates and times, finance, engineering, text, and more.

## Formula Basics

A formula cell displays the result of its calculation and, on the surface, looks like any other (nonformula) cell. By just looking at a table, you can’t tell the difference between a cell that contains a formula whose result is 6 and a cell that contains the number 6 (the number typed in directly). It’s crucial to distinguish a formula’s two display components: the formula itself and the resulting value. The actual contents of a formula cell is an equation—the formula—that tells Numbers how to generate that cell’s value. It’s that value, and not the formula, that’s used in any calculations that refer to the cell.

To view a formula:

Double-tap the cell containing the formula.

Numbers opens the formula keyboard and displays the cell’s formula in the formula bar above the keyboard .

Ignoring the technical details for now, take note of the basic traits common to all formulas:

• You enter each formula into a single cell. A formula can reference other cells on the spreadsheet, but the entire formula itself resides only in the cell where its result is displayed.
• Numbers recalculates the result of a formula every time you open a spreadsheet or change a data value that the formula uses. In , for example, if you change any Test 1 score, Numbers auto-updates the value of the formula cell showing that column’s average. For small tables or simple formulas, updates occur instantly; for large tables or complex formulas, updates are slower.
• Formulas can operate on and display results in any data type: numbers, text, dates, times, durations, and Boolean (true/false) values.