Formula in Excel 2013
How to count cells by criteria
Use COUNTIF if you need to sum values for a particular person or other criterion.
How to sum cells by criteria
Use SUMIF if you need to sum values for a particular person or other criterion.
Hide formulas from appearing in the edit bar
Usually you can view a formula in the Excel cell when cell is selected, but you can protect spreadsheet to hide formulas in some cells.
Calculating the difference between two time stamps
Because time stamps are represented as serial numbers, you can subtract the earlier time from the later time to get the difference.
Solver tool allows you to specify multiple adjustable cells and constraints on the values that the adjustable cells can have, generate a solution that maximizes or minimizes a particular worksheet cell, generate multiple solutions to a problem.
Goal seeking is a useful feature that works in conjunction with your formulas. If you know what a formula result should be, Excel can tell you which values of one or more input cells you need to produce that result.
Calculating the number of work days between two dates
When calculating the difference between two dates, you may want to exclude weekends and holidays.
Calculating the number of days between two dates
A common type of date calculation determines the number of days between two dates.
Counting the number of unique values
You can easily count the number of unique values of the range using a simple formula.
Excel Formula auditing tools
If you would like to better understand how some of these complex array formulas work, consider using a handy tool - Formula Evaluator: