Inserting current date and time

Hit Ctrl + ; to add the current date

Hit Ctrl + Shift + ; to add the current time

Functions

String functions

SUBSTITUTE

SUBSTITUTE(text,old_text,new_text,instance_num)

Text is the text or the reference to a cell containing text for which you want to substitute characters. Old_text is the text you want to replace. New_text is the text you want to replace old_text with. Instance_num specifies which occurrence of old_text you want to replace with new_text. If you specify instance_num, only that instance of old_text is replaced. Otherwise, every occurrence of old_text in text is changed to new_text.

ISBLANK

checks whether a cell is empty