# Jon Wittwer

About the author: Jon Wittwer is the founder, president, and editor of Vertex42.com. In 2003, Jon combined his interest in web development with his love of Excel to create what would become the Vertex42 you see today. Jon has a Ph.D. in mechanical engineering, but now spends the majority of his time creating, improving, and writing about the spreadsheet templates that are being used by millions of people and businesses all over the world.

## How to Use Conditional Formatting in Excel

Learn over 20 different ways to use conditional formatting in Excel to do things like add color scales for data analysis, add data bars for in-cell charts and progress bars, and create a gantt chart.

## Custom Number Formats in Excel

Learn how to create and use custom number formats in Excel to display numbers in thousands or millions, add units such as “ft” or “lbs”, change font colors, add special symbols, and more.

## Create a Running Balance in Excel that Allows you to Insert, Delete, and Move Rows

A basic running balance formula can lead to hard-to-detect errors. Learn two ways to create a running balance in Excel that doesn’t break when you delete a row, insert a row, or move rows via cut and paste.

## Introducing the Savings Snowball Calculator

Vertex42 has developed a new Savings Snowball Calculator to help you plan how to reach your savings and debt payoff goals. This article provides some background on the savings snowball concept and explains some of the features of the calculator. Questions and comments are welcome.

## Array Formula Examples – Simple to Advanced

In Excel, an array formula allows you to do some powerful calculations that you might not be able to do any other way. Learn how to use both simple and advanced array formulas, including nested IF formulas, sequential number arrays, and matrices.

## Text Manipulation Formulas in Excel – The Ultimate Guide

This is the ultimate guide to using Text Formulas in Excel such as SUBSTITUTE, LEN, CHAR, CONCAT, TRIM, LEFT, RIGHT, MID, FIND, SEARCH and others. The examples start simple and then build up to more advanced formulas including cleaning up data, splitting text into columns, and converting strings to arrays.

## SUMIF and COUNTIF in Excel

SUMIF, SUMIFS, COUNTIF and COUNTIFS are very powerful functions for data analysis. The hardest part is learning how to define the criteria for different types of comparisons. This article shows examples of all the different criteria types, including matching blank and non-blank values.

## Debt Payoff – A Good Investment?

Taking a break from Excel tutorials, this article compares paying off credit card debt to investing. Take an in-depth look at interest rates, liquidity risk, limited return, risk of principal loss, and tax efficiency. Perhaps debt payoff is really my best investment.

## Volatile Functions – What’s the Big Deal?

A Volatile Function such as RAND, TODAY, OFFSET, or INDIRECT is recalculated every time Excel recalculates. That may be a problem, or it might not be. This article explains why volatile functions may slow performance and also explains why I love them so much.

## Dynamic Named Ranges in Excel

A Dynamic Named Range is an awesome way to reference customizable lists. This article explains how to use OFFSET, INDEX, INDIRECT, CHOOSE, and IF to create dynamic ranges. It also explains formulas for finding the position of the last value in a range.

## Create a Drop Down List in Excel

I love using drop down lists in Excel. In this article, I’ve tried to explain all of the techniques that I use for making drop-down lists, including simple yes/no options, checkbox substitutes, dependent lists for sub-categories, and using dynamic named ranges.

## VLOOKUP and INDEX-MATCH Examples in Excel

Learn how to use both VLOOKUP and INDEX-MATCH and other powerful formulas to do lookups in Excel, from simple to advanced formulas, including multiple criteria and case-sensitive lookups and to get the last value in a range.

## Use DATEDIF to Calculate Age in Excel

Learn how to Calculate Age in Excel using DATEDIF and other Excel formulas. Calculate age in years or a combination of years, months and days. Learn an accurate work-around for the “md” option.

## How to Create Custom User Defined Functions in Excel

Learn how to create your own custom functions in Excel using VBA. This articles explains the pros and cons of user-defined functions and provides examples.

## Experts Share Their 10 Favorite Excel Functions

20 Excel experts share their lists of favorite Excel functions. If you want to get more out of Excel, try using these functions in your work.