Inputting Numbers Into A Textbox And Formating The Numbers?

I just D/L VB express 8, and I'm trying to learn how to use it. what I'm trying to do is write some code that:takes a number into a text box (textbox1.text)do some simple calculations with that number when I press a button (button1)display the results in a second text box 9textbox2.textThe first problem I am having:The numbers are in the "milli" range, meaning to the power of negative three, so 10^-3 = 0.01 I do not want to enter 10^-3 or any other exponent into the textbox, I am simply entering in 10 because all my units will be in milli. I've tried using exponent and scientific notation but it doesn't calculate correctly. I've done a "work around" to get it to do what I want, but there has to be a simpler way to achieve the above results without. for example, the user enters 10 into the textbox, the button multiplies 10^-3 *30, as a crude example, and stroes that value (say, B=10^-3*30) and B is DIM B as Double.

Problem number two:Error checking. I need to validate that only numbers can be entered into the textbox, or else the program will display an error message (messagebox). I can achieve this to some degree with sample code from here and other places, but, some of the code does not take into account that some numbers have decimal places (I have foud code that does, and it does work), but if a users enters, say the letter "E", it crashes the program. If the user enters "10.3Z", it crashes the program. I cannot seem to code for the last case, a mixture of numbers and letters to get an error message box.