Mod Operator

You can find the remainder in Integer division by using the modulus operator (mod)
The Mod operator returns the remainder after division.
This is similar to the integer division except it only returns the remainder.

8 Mod 3 = 2 
10 mod 3 = 1 

Even Numbers

x Mod 2 = 0 

Odd Numbers

x Mod 2 = 1 

Loops

This is extremely useful when you have a loop and you want to perform an action every nth times through a loop.

For icounter = 1 To 100 
   If icounter Mod 10 Then 
      'every tenth value
   End If 
Next icounter 

Maths Formula

This is actually equivalent to the following maths formula

a - (b * (a \ b)) 
a - (b * Fix(a / b)) 

Very Large Numbers

You can also get overflow errors in VBA using the Mod operator with very large numbers. For example,

Public Sub Mod_Error() 
    Dim Number As Double 
    Dim Divisor As Double 
    Dim Result As Double 
    Number = 2 ^ 31 
    Divisor = 7 
    Result = Number Mod Divisor ' Overflow error here.  
End Sub