What excel function you usually use in your day-to-day activities?

I agree with all mentioned formulas above, especially vlookup.
According to my daily data search and auto-self training on excel works, I used the following formulas for their corresponding uses:
1- SHIFT+F3 to insert any required function
2- SHIFT+F10 to use shortcut menu functions
3- column or raw selection by CTRL or SHIFT + space-bar, respectively.
4- SHIFT+F2 to add comments.
5- CTRL+F11 to open new worksheet
6- AVERAGE, SUM.
COUNT, COUNTIF, MIN and MAX for calculations.
6- DSTDEVB for standard deviation in statistical estimations..

vlookup

SUM , COUNTIF , AVERAGE , INDEX , VLOOKUP

Commonly the Sum() is used in excel.

M-S Excel is most useful Application for an accountant, I usually use almost all the functions in my day to day activities

Countif, Vlookup, Index Match, Sumproduct, Date functions..

vlookup,pivot table.filter,sort and calculation functions

SUM , COUNTIF , AVERAGE , INDEX , VLOOKUP

count if

I am using Exel function for Making calibration report for plant instrument

VLook Up