If the objective is to shorten the code. perhaps this could help. (algorithm only)
// algorithm only, cant seem to remember VB as its been 14 years since i did any VB
dim baseValue as double = 0.28
dim multiplyFactor as int = 0
dim resultBase as int = 25
multiplyFactor = (int)((double)TextBox6.Text/baseValue)
TextBox4.Text = multiplyFactor * resultBase
TextBox5.Text = multiplyFactor <=3 ? multiplyFactor : "3+!"
P.S. No exception handling and proper type conversion being done in the algo.
P.S.S. Where is my prize now :)