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Chapter 9

Using Math Functions

In This Chapter
Rounding off numbers in a spreadsheet
Using functions for calculating products, powers, and square roots
Summing the products in cell ranges or arrays
Doing conditional summing

he Math & Trig group of functions includes a wide variety of mathematical functions for
Tcomputing new values as well as for controlling the results of calculations. This group
also includes a large assortment of trigonometric functions most often needed in engineer-
ing and scientific endeavors. In this chapter, you get a chance to practice using some of the
math functions more commonly needed in spreadsheets for business applications.

Rounding Off Values

Rounding off the numbers that have fractions is one of the more frequent tasks you may
undertake in Excel. Excel includes three functions in the Math & Trig category that you can
use for rounding off the numbers in a worksheet:

ROUND(number,num_digits) to round the value specified by the number argument to
the number of digits specified by the num_digits argument
ROUNDUP(number,num_digits) to round up the value away from 0 (zero) that is specified
by the number argument to the number of digits specified by the num_digits argument
ROUNDDOWN(number,num_digits) to round down the value toward 0 (zero) that is
specified by the number argument to the number of digits specified by the num_digits
argument

Q. What’s the difference between using one of A. Formatting a number only changes the way
Excel’s rounding functions to round off the value appears in the cell, whereas
values to a particular decimal place and rounding off a number with one of the Excel
using a number format to control how functions actually changes the number of
many decimal places are displayed? digits in the value entered in that cell.
Try It

Exercise 9-1: Building Formulas the ROUND, ROUNDUP, and ROUNDDOWN
Functions
If Excel isn’t running, launch the program and then open the Exercise9-1.xls workbook
file in your Chapter 9 folder in the My Practice Spreadsheets folder inside My
Documents on your hard disk or in the Excel Workbook folder on the workbook