Use these articles to learn more
What is Excel SUMPRODUCT formula and how to use it?
at 10 November, 2009
How to Round and Sort Data using Excel Formulas?
at 6 July, 2009
Excel Formula Errors – Understand and Debug Them
at 20 April, 2009
Excel Formulas – Explained in Plain English
at 24 November, 2008
Extracting Unique, Duplicate and Missing Items using Formulas [spreadcheats]
at 6 November, 2008