Simple functions
SUM – sums all numbers
AVERAGE – arithmetic average
MAX – finds the largest number
MIN – finds the smallest number
COUNT – counts cells with numbers
COUNTA – counts all filled cells
COUNTBLANK – counts empty cells
PRODUCT – multiplies all numbers together
ROMAN – Converts a number to a Roman numeral
ROUND – rounds numbers
Text functions
PROPER(text) – capitalize the first letter of each word
UPPER(text) – all letters in uppercase
LOWER(text) – lowercase all letters
LEFT(text;number) – characters from the left
RIGHT(text;number) – characters from the right
MID(text;start_number;number_of_characters) – characters from the middle of the word
FIND(search_text; text) – finds the position of the character in the text
SUBSTITUTE(text; old_text; new_text) – replaces characters or words
LEN(text) – the number of letters in the text