This is the table
0 & 0 = 0
1 & 0 = 0
0 & 1 = 0
1 & 1 = 1
This is the truth table of the AND bitwise operator. In programming language every single thing is transalted into bytes, and smaller bits.
1 byte=8 bits.
Here are some info about bits: http://en.wikipedia.org/wiki/Bit
So, in your case you had a for from 0 to 9, all of that bitwise and with 1 (i & 1).
First of all we will translate every single i into binary:
For Each ctrl As Control In Me.Controls("pnlMainPanel").Controls
If ctrl.GetType Is GetType(System.Windows.Forms.Panel) Then
For Each subCtrl As Control In ctrl.Controls
If subCtrl.GetType Is GetType(System.Windows.Forms.TextBox) Then
If subCtrl.GetType Is ...