Please refrain from name calling. Salem is a great poster and has some very good advice. you did not post any code or say what this is for so even i though it was asking for homework help. it is best to clearly state what is going on becuase we have no information to go on besides what you have posted.
with that siad i would suggest 2 loops. since you could have multiple's of the same number as a factor. the first loop would run through each digit and the second loop would divide the number as many times as it can by that number. a for loop and a while loop would probably work great.
a good example is the number 8. its factors are 2-2-2 but with your code as above you would get 2-4 which is not correct. my approach would test 2 multiply times and give as an output 2-2-2.
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 ...