What is the use of increase decimal in Excel?

Answer 1

This function has to do with the format of a cell and how many decimal places are shown. Applies only to numbers. Keep in mind that the actuall value is unchanged. For example, the number will be rounded if you specify 0 decimal places.

Answer 2

It allows you to see more decimal places, to display a more accurate result from calculations. Excel will round values to the nearest decimal place. So if you typed in 2.458 into a cell and it was formatted to show 2 decimal places, you would see 2.46 instead. It will still retain the real value for actual calculations, but you will only see the values to the amount of decimal places set. So if you are dealing with calculations that result in lots of numbers that have longer amounts of decimal places, like when doing averages, sometimes it is a good idea to increase the amount of decimal places. That is why the facility to both increase and decrease decimal places are available. It saves having to go into the format options to change them.