## 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.

### Using Solver

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

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.

### Excel Formula Evaluator

If you would like to better understand how some of these complex array formulas work, consider using a handy tool -

**Formula Evaluator**:### How to avoid misleading numbers

Applying a number format to a cell doesn't change the value, but only how the value appears in the worksheet. Formatting can play a joke with you, e.g., sum of values seems incorrect because Excel displays a limited number of decimal places and their sum is not equal to the real sum.