# 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.

## Custom LAMBDA Functions in Excel

Introducing the LAMBDA Library – A collection of fully documented new functions for Excel that you can use right now, including array and matrix manipulation, interpolation, eigenvalues and a newton-raphson solver.

## Multiple-Variable Data Tables in Excel

Learn how to set up x-Input and x-Output Data Tables in Excel! With this technique you are no longer limited to 1-D or 2-D!

## Dynamic Arrays in Excel

Learn need-to-know information about Dynamic Arrays, the spill behavior, and many of the new functions such as SEQUENCE, VSTACK, FILTER, TOCOL, etc.

## Just for Fun – Spreadsheet Themed Playing Cards

Are you a fan of spreadsheets AND card games? If so, check out this new project, just for fun: Spreadsheet-themed playing cards and a crazy card game.

## Gantt Charts Made Easy – New Version 5.0

In December, 2020 we released a new version of Gantt Chart Template Pro that is designed to consolidate multiple versions and features into a single template. It is available to both new and current customers. Existing customers can return to the download page to get the new version (no new purchase necessary). When I first [...]

## Excel Suggestions You Can Vote On!

Learn how to make and vote on feature suggestions for Excel, using the official Microsoft website. In this article, I have listed some of the features that I would like most, so please vote on them!

## 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.