In your opinion, what are a few of the most useful functions in Excel? How do you use them?

I think you should know functions in their categories.

like functions of text, date and time, database, search and lookup, range, math, ... etc.

for each category you should know the most used functions.

Thank you for the question

Cheers

first you should know what are the useful function then you will know how to use it

sum , average , min , count

According to my opinion sum calculation is a great function of excel.

AVERAGE FUNCTION

PROJECT FUNCTIONS e.g NPV , PBP IRR ETC

SUM FUNCTION

SUBTRACT FORMULA

SPELLWORDS FUNCTION

IF FUNCTION

NESTED IF FUNCTION

VLOOKUP FUNTION

MULTIPLICATION FUNCTION

DIVISION FUNCTION

PERCENTAGE FUNCTION

DATE FUNCTION ETC

Pivot is one. Makes sorting, creating reports and analyzing numerous data easy as pie.

Vlookup ( to comparison of two columns in different worksheets or same worksheets)

Sumif (to sum the quantities using the condition for speicific column or row in a worksheet)

Conditional formatting (as the name indicates you want to check, used for comparison of two cells or columns or rows)

Concatenate ( to combine two or more cells)

Pivot Table ( to summarize larger worksheets in a summarized way to look into desired results)

The most useful functions in Exel are the function of graphs and mathematical equations

Vlookup, retrieves required value from a desired column which is related to the searched criteria which is avaliabel in another column. Eg. Column 1 has names, column 2 has ages of each names, If you need the age of a particular person in another cell it can be vlookuped.

Hlookup, same as above but this is to retrieve data of Rows instead of columns as above mentioned.

Defining cell name: By defining cell name we can easily retrieve the data in that particular cell if the name is unique. For eg if we put fuel value in one cell and changes the cell name a1 to Fuel when the value fo fuel is input. we go to another worksheet or any cells of the same file and put=Fuel, the cell will displays the value of the fuel.

Goal Seek: We can achieve a final target by changing one cell and with out disturbing a 100 cell. just in one go.

Text to columns: Downloaded dats from SAP, ERP or any other data bases some times have semicolumn or space etc to differentiate between each value and will be displayed in one cell of excel. This can be easily sorted based on the type of speperation used.

perceptual map for positioning analysis, also the coefficient, range, forecasting, all data analysis method

It all depends on how and why you use Excel! But the essencial ones in my opinion are IFs, IFERROR, COUNT, COUNTIF(S), LOOKUPs, etc. Because these functions can ease any analysis you do on Excel.