excel training course london - Symbols in formulas

$ represents an ABOLUTE VALUE in a formula, not a currency.
This means that the cell referece you are using, when copied, will remain the same. There are combinations of the $ symbol ie:

A1
$A$1
$A1
A$1

Basically, the $ sign locks the row or column that it proceeds, when the reference to that cell in a formula is copied to another cell.

The ! symbol is used in formulas that contain references to other sheets in the workbook.
So if you are on sheet1 and you typed in =sheet2!A1 , the result would pull the value from sheet2 and the cell A1.